I understand that the a/c will create a certian amount of pull on the engine with the defroster turned on. Mine seems excesive. On a rainy day like today, I'll use the defroster to keep the windshield from fogging up. With the defroster or the a/c on the car jerks hard like a missing cylinder or maybe even a little harder than that. Pulling up to a stop in neutal the tac will drop nearly to 0 then the computer will compensate and shoot the rpms to about 1800. It doesn't do this on dry hot days running the a/c. Some but barely noticeable- only when it is damp out. I'm guessing it must be some sort of sensor problem but I'm really pretty clueless as to which one or am I totally off the mark alltogether?

 

Is that when accelerating?

The screwy RPM at idle and decel is probably the Idle Air control lagging. Pull it out, clean it, put a new gasket on it and slap it back on.

 

Accel and deccel. It doesn't seem to make any difference what the rpm range is either. I tried about 3000rpm steady in 1st gear and it was jerking then too...

 

Thanks Derf00. I'll give that a shot.