No other problems with the car. AC cold, everything works perfectly. Has 258K miles and drives like new. But at low rpm, like stopped at light, when AC is turned off engine dies. When car is moving and turn the AC off then engine runs as long as car is moving, but when come to a stop even a few minutes later engine dies. If I keep the AC running and put it in park, engine 'almost' dies with whole car vibrating and couple of seconds later rpm goes to normal range and smooths out. Engine starts right up like nothing happened every time. I'm used to it but I'm concerned when my wife's driving this car(very rarely). I can totally see her freaking out. Is this classic sign of bad IACV? I cleaned the TB and IACV. Being that it is a 93, IACV is not serviceable. Any suggestions?

 

I think that the iac is stepped more open when the ac is turned on, I don't know what else would bring up the idle when the ac is on. Look for vacuum leaks, hoses off, holes in hoses etc.
When was the last huge tune up done timing belt and that sort of thing? Are there any codes?

 

TB/WP/plugs were all done around 200K. Intake tubing has some cracks where clamps go but I doubt that's the issue. No Check engine light or anything

 

How does it run when started cold for the first few minutes?

 

I dont know about California but here in Texas, that would be a smart car, when the AC goes off, get out of the car and go into the house... (hehehe) I am with dicer, you seem to have some stepper motor trouble.. my idle is about 300ish higher with AC...