Idle problem help needed

[stormbringer]

I still have this idle problem on my ride, hope somebody with the similar problem have theirs fixed and share it with me.
1994 galant AT

1. when I start the car, idle runs smooth at 800 rpm
2. when I turn on the aircon, the RPM goes down a little and slowly rises up for the engine not to vibrate
3. when I STEP on the BRAKE and put it on DRIVE or REVERSE, the RPM drops to 400 or 500 RPM that makes the engine vibrate.
4. the RPM will drop more if I turn on the headlights.
5. When driving with aircon on, and on a stop, the engine vibrates and RPM is on 400-500. and sometimes the idle pulsates up,down,up,down.

Things that I did:

1. Cleaned the throttle body ( I made sure its free of dirt).
2. Cleaned the IACV
3. Checked and tested the IACV motor. ( IACV motor runs fine. it goes up and down when tested on a 9 volt battery)
3 Cleaned the MAF.
4. Checked all the vacuum hoses (no leak, seems ok)

I have done all this things so far that is connected to the idle problems. But the problem remains. can anybody help me or give me an advice what to check next. I was also thinking of the ECU if its sending signal to the IACV to activate ( I did'nt checked the continuity yet). but before I go to that conclusion please somebody help me if there is still other things to check before I go to the ECU. thanks and please help:

[afrasay]

Ah did you try to reset the ECU by removing one of the battery terminal?