what's the deal with this??? it doesn't happen all the time but, it only happens when the AC is on and maybe the heater. what is causing this? it's a 94 FWB.
THANX

Sounds like you're drawing too much current. If the lights, wipers, and defroster are all on, and the car won't run, it suggests that the load is so great that the alternator load causes the engine to stall. You could also have an idle control prolem, which is not adjusting the idle to compensate for the increased electrical load. It could also be something as simple as corroded battery terminals (pop 'em off and file 'em a bit 'til they sparkle) or a defective voltage regulator/alternator. I'd start with a charging system voltage test and go from there. If that seems OK, connect a tachometer, turn on the headlights, then the wipers, then the defroster/AC. If there's no increase in idle speed as the electrical load increases, you could be looking at an idle control problem. One reason this may be intermittent is that there is a significant load imposed by the cooling fans, which are not on all the time. So if your idle compensation is incorrect, the fans + the wipers + anything else are just too much for it. Scan for codes and make sure the power steering pressure switch is OK. A defective PSP will cause intermittent stalling problems too.