power loss with heater on

[ariesdude]

Engine 1.6L DOHC 4 Cyl ATX

Last week i noticed that this weird power loss thing goes away about 5 mins after i turn off the heater (not the blower, just moving the temp control knob all the way to cool side). When i have the heater on then the car has no power or torque and i have to mash the gas pedal and get it slowly upto 2.5-3.5k rpm and then the car limps upto 40 or 45. But if i turn off the heater - approx. 5 mins later i barely have to touch the gas and it gets up to 2.0 or 2.5k rpm in no time and 45 or even 55 easily. (My car doesnt have AC). I did a controlled test on a deserted road today with the heater on/off and it is definitely confirmed.

First i thought air pockets in coolant - i ran the engine (parked) for about 15 mins with the rad cap open. There was some bubbling at the cap area after 12 mins - but the situation is still the same. I am thinking of getting a rad flush soon. But what else do you guys think i should look at to rectify the problem? maybe thermostat?

Also everytime i crank it - it takes 3-4 engine rotations to catch up and start firing - is that normal - or does something else need to be looked at?

Ignition Stuff
New Spark Plugs/wires
Disty Cap/Rotor
HEI mod - no ext coil (external coil coming soon)

Other stuff
Relatively new coolant thermo sensor, o2 sensor
Air filter, fuel filter
GS alternator swap

[alex3ohio]

Maybe a fuel pump? I have no clue why the heater would affect anything but the problems with turning over could be a fuel pump problem.