Idle/running problems

I have a 89 Pontiac 6000 LE with a 2.8L V-6 and 126000 km on it. When the car warms up a little bit and I stop at a stop sign or traffic light, the rpm drops to 500, it almost stalls and has stalled once. I had the intake manifold and fuel injectors cleaned but that didn't work out. I did the "Idle relearn" procedure, but that didn't work either. I'm thinking that it could be the ECM or the IAC. I also noticed that when I turn on the A/C, the engine doesn't rev higher, which it should, it justs revs even lower. I also just changed the battery recently because it died out completely (last week)

Could it possibly be the torque lock converter

I had that same problem, it's your air idle control sensor. Be ready to dish out 'bout $150 bucks.