Perform the idle reset procedure to adjust the range of the IAC.
Step #1, clean the IAC.
Start the engine, open up the throttle stop screw to raise idle and then unplug the IAC. Now, unscrew the idle stop screw to lower the idle down.
Lower it to a low steady idle. Only drop it as low as you feel confident it won't stall.
Now, unplug the battery for 30 mins to reset the computer.
Hook it back up, plug in the IAC and start the engine. Let it idle 2 mins.
Now turn everything on (ac too) and let idle 2 min.