1988 Ford Taurus stalls

I have a 1988 Ford Taurus 4cyl. fuel injected engine. The car stalls at idle. I have replaced the ignition module, fuel filter, done major tuneup including injector cleaning. Sometimes the car restarts immediately and sometimes it takes about 5 - 10 minutes. When it is running under load (at speed) it runs fine. Any ideas?

[b]The next time the engine wants to stall, try stepping on the accelerator lightly. If this prevents the engine from stalling, the most likely problem is a defective Idle Air Control motor.