Really bad exhaust problems

[im2bad4ya]

I recently replaced my broken catalytic converter (on 8/9) and also added a resonator and a new muffler and O2 sensor (because i had diagnosis code 17). I drove my car sparingly with the broken catalytic converter for about 3 weeks, but it wasn't too bad, just drove when I had to with the windows down and couldn't tell there was an exhaust leak (seriously not bad at all). But since fixing the exhaust, my car is decidedly worse! It billows a blackish/bluish smoke (can't tell really). But when the car is idle for about 2 minutes or more, it is ENGULFED in exhaust smoke, and the smell is unbearable. It idles regularly at about 750 RPM but when I give it gas at 2K RPM the engine starts to rattle (possibly a timing issue or misfiring cylinder). The mileage has suffered and drinks gas. I ran diagnosis but no codes come up. I can honestly say I would rather drive the car when it had the broken CC than now that it's 'fixed.' Also, I hear a sound coming from the throttle body, as if it is being blocked, clogged and it's not getting enough air. Maybe I'm being paranoid, but it is a distinct sound.

So even though I got the car fixed a few days ago, I'm not sure if I'm supposed to run the car so the computer can program itself to use the proper amount of gas, but I definitely plan on taking it to my mechanic to get it checked out. For now, I want to know if anyone can give me some help, perhaps they had a similar issue, know what's going on or if there is something I can do myself (check under the hood, use additives, etc) to perhaps get a better idea of what to fix.

[Ryan]

Sounds like bad ignition timing, or a dead cylinder. Burnt valve or collapsed rings. Super bad headgasket....

Try a compression test.

[im2bad4ya]

okay........pretty much confirmed, dead cylinder, bad headgasket ......brown coolant, black oil, just a matter of time before my engine dies..........but there is a light at the end of the tunnel. I managed to find a '94 BP engine with 79K miles for $300 at the local junk yard. If the inside looks good i'll take it and swap it in! Turning a crisis into an opportunity.....wish me luck