I searched for this topic but only found out how to ADJUST the IAC motor. My car is running like *** at lower speeds and I think this is the problem but would rather be more definite before throwing $50 out the window...

Why do you think that's what the problem is? Is it setting a code?

I'm curious also. My book has a flowchart on how to test but it requires a scan tool, which I don't have. Sometimes when I put it in reverse the idle goes down to about 400 then goes back up to about 550 or 600. I've cleaned the IAC but didn't really help. Any way to check without a scanner?

I've never tested one, just set and replaced them, but think I recall seeing an IAC tester at autozone last month. Maybe somebody knows something about that and can help out?