Rough Idle/Stalls when braking... (putt putt putt putt putt)

[Demonic1]

I've been having a really rough idle for the past week or so.
It started about a week ago. I was out driving and hit a stop light. Downshifted to 1st then Neutral, and applied the brakes. The RPMs dropped from 750 to dead in a split second. She died. I turned her over and she started right up. I turned everything that put load on the engine off. (Stereo, Fans, etc.) I got another block down the road and hit another red light. Neutral, then brakes, then dead. I adjusted my idle (GRD+TEN method followed) so it was less likely to die. I dropped off my passenger and headed home.
Current symptoms =
The idle is really rough (1100 +/-300 RPMs)
Putt putt putt sound from exhaust (like it's not a complete burn in the cylinder)
When I apply the brakes at idle the RPMs drop by 8-900
Current testing =
Checked timing
Rebuilt my alternator
Replaced the ignition coil
Checked for vacuum leaks with spray
Checked for short in brake lights
Gonna put on a new Dist. Rotor and Cap... later... when I get energy
Did search on website... which lead to the vacuum testing.

I recently replaced my head gasket. Previous gasket was blowing cylinders into coolant.
Did the timing after that (again). I snapped a timing belt 2 months (or so) back.

[Demonic1]

I replaced the Dist. cap and rotor today.
New symptoms = apparently it runs fine when she's cold. Once she warms up, she starts the puttputtputtputt.

The fact that she does this while warm leads me to think that it's not a timing issue.
It also starts while she is warming up. Not when she is warmed up. The heat is still in the core of the engine. I'm thinking it may be the distributor itself.
May also be some part of the engine opening up and losing the vacuum... but I already checked the engine for leaks. Time to check again.

[mxmikey]

If it is a vaccum leak you will notice your break's aren't working very well. Does a check engine light come on? If so what does the code say?

[Daninski]

Could it be a vacuum leak at the brake MS. Disconnect the line to the brake, plug it and start the car. Does it idle fine now?

[Demonic1]

Brakes work fine until she dies. Then power brakes don't work.

I disconnected the brake line while she was off and it had a vacuum.
I plugged it and she ran the same. Brakes however didn't work the same.
I ran the car for a bit to build up the vacuum in the brake booster.
Hit the brakes a few times, then disconnected it again and it had no vacuum. (not sure if it's normal like this)

I'll pay a neighbor kid to come hit the brakes while I'm under the hood. Listen for leaks and such.

I replaced the entire distributor with the known working one off my Protege BP swap.

Still has idle/brake issues.

***edit***
Forgot to mention... There are no CEL codes showing up.
I pulled the battery for 10 minutes, then let her run for 10 minutes and still got no codes.

[mxmikey]

Before you replace the ditsy wear rubber gloves and have the car idling, while idling disconnect the spark plug from the wire, hold the wire about a quarter inch above the plug, and listen if there is a ticking of the spark jumping back and forth.

[Demonic1]

Here's a new avenue I didn't think to explore.

When the car first started to act funny and I pulled off to check for a simple fix, the fuel pressure regulator control solenoid valve was disconnected. The wires had wiggled loose during driving or something. I tightened them and reattached them. I'm wondering if either the solenoid or the regulator might have gone out. If it was starved or putting too much fuel in it would run like crap right?

I'll check it tomorrow for voltage, I'll check the solenoid for function, and have no idea how to check the actual regulator (on the fuel rail).

Any ideas?

[PilotSmack89]

It's gunna sound stupid and simple, but imma say it anyway...

I had a goofy stumble/sudden RPM loss during downshifting until a week ago. Only thing I did was (aside from regular oil change) new fuel filter and new plugs.

[Demonic1]

Ok, so I replaced the fuel pressure regulator solenoid. It's still running the same. The regulator solenoid is getting voltage.
I haven't swapped the fuel filter, but I put a (temp) bypass in place and it still ran the same.
The distributor is already swapped. But it it still getting a good spark (Checked with spark tester).
Haven't swapped the plugs out. (Unemployment ran out, can't afford parts or food)
Oil is <10k miles old.
I checked for vacuum leaks again. Nothing found. Again.
O2 sensor looks to be working. I took it off and checked the resistance change with a torch and a voltometer. O2 sensor was not fouled.

While running her, I could smell unburnt gas. I'm thinking of getting hotter plugs. I'm also thinking it might still be the fuel pressure. If there was too much pressure behind the injectors, they would put too much in right?

Also still running the stock airbox... I'm wondering it it'd run better without the air filter in the way (just for checking). My cousin "cleaned" my paper air filter with K&N oil. I'm not sure if it works like that?

[Demonic1]

So the past couple months the issue has been intermittent. This past month though, it has been constant.
When I started it this morning after cleaning the old IAC and it fluttered the rpm range rapidly (2000, 1500, 2000, 1500, 1750, 1250, 1750, 1250, 1500.... ) until it settled around 1200.
When I push the brake pedal it completely kills my car.
I have my idle adjustment screw all the way out.
My idle tends to run ~1500, though sometimes it sits ~1000 without anything running.
It doesn't seem to die while cold. Dies cold or hot...
New battery, alternator rebuild ~6months ago. Replaced vacuum hoses & coolant lines.
Brake lights, stereo (300W amp), power steering and radiator fan will kill it when activated.
I swapped the MAF out today with no change.
I swapped the IAC out with no change. (spare parts from tracer engine)
I forced a vacuum leak via the cruise control and the idle jumped and remained steady. ~1700-2000
I checked the breather hose for leaks with brakeleen. Then in a dark room with a flashlight.

[Sleeper6]

I know you dont have a CAI but I had the same issue on mine when the breather that goes to the intake manifold to just post VAF had a SMALL SMALL leak it caused my car to die every time I tapped the brakes b/c the car was trying to make the excess vacuum for my brakes and loosing unmonitored air. So if you cant afford parts, go over that area intently, with the car running push/pull/prod on any vacuum lines/connections to simulate a leak that would only be present when the cars in load as the engine/transmission moves in the mounts.

[Ryan]

also, the brake booster is vacuum operated, so if your booster canister has a leak, the engine will draw consistent vacuum through it.... take the hose off the manifold, and suck on it, get someone to hit the brakes, and see if it holds vacuum.

[Demonic1]

Alright, so I had a hell of a time getting it started this morning. It appears the issue keeps getting worse.
I checked the IAC (ISC?) Idle speed controller with my voltmeter and it's reading 12.4 (book says 10.7-12.3 @ 68F) steady across temp ranges.
The valve inside did not appear to move at any temp from 40F-150F.
This testing was done on the initial one. I still have the spare on the car.
I'm going to check the resistance on my TPS in a minute.

On the vacuum note. While off, if i unplug the booster from the manifold, it sucks like it has a vacuum. If I press the brakes 2-3 times it has no vacuum. Is this what you wanted me to test Ryan?
I'm a little limited on what I can do, as I have no neighbors. My 4 y/o can't reach the pedals yet. I live in cow country.

****edit****
I checked the TPS and it measured fine.
With nothing running I was able to get a stable warm idle at 1400.
The brakes caused the car to die, the headlights dropped the idle to 1100 without killing it, the stereo and sub did nothing to the idle, turning the steering wheel (power steering) caused the idle to drop ~600.

[kakarot135]

Throwing it out there becauit happened to me. Check the tube from the maf to the intake manifold if there is a crack it will cause a bad read and idle issues. Also did you try to take off the maf if so did you remove the screws. If so check the connections it controls the fuel and spark. Just a thought.

[Demonic1]

So, I had a hell of a time getting it started this morning. I ended up forcing a vacuum leak to get the car to start. I opened the nipple for the cruise control and she started right up.
With the vacuum leak it threw a CEL code. 15 and 17. O2 Sensor.
Reset the codes.
I replaced the O2 sensor and she started running a little better. But still died while pressing the brake (without vac leak)
I talked with the guy at the parts store and he said to check my plugs and wires. My plugs weren't fouled, but #2 & 3 looked like there was arcing happening. I replaced the whole set. My wires resistance was 6kohm, but the manual say they should be 16. Replaced them too.
Running some injector cleaner too.

Since a forced vacuum leak causes her to run about where she needs to, I'm going to hunt for a blocked vac line.