Question: would a sticky IAC valve be the cause of idle speed changing? Most of the time the car idles at 7-800, but every now and then it will drop to 600ish. If I blip the gas it jumps back to the 7-800 mark.

If this is the case, should I just replace the IAC or is there something I can do with what's on the car?

Does the RPM drop correspond to A/C cycling (if you still have A/C)?

Any chance the throttle blades are hanging up a bit, and suddenly releasing?

Shoebox's IAC Check:

http://shbox.com/1/iac2.jpg

Any access to a real time PCM scanner, which allow you to observe how the PCM responds to the RPM drop, with respect to IAC counts?

I have an Actron scanner, I should be able to watch it from there. I have opened and closed the TB a number of times (hot and cold), and don't feel anything catching. No A/C on the car right now.

I will try to look at this over the weekend. Thank you Fred!