Did you mean IACV? Idle Air Control Valve? I just wanna make sure cause I'm having sort of the same issue.EACV.
My Idle is a little differernt than yours tho. Mine will Idle fine at 900 most of the time. Sometimes it will start to drop, almost to choking out, then bounce back up again. I tried the TPS, that didn't work. Next is the IAC valve.
Baker, for yours, I'd check your throttle position sensor. They aren't that hard to test if you don't have a spare laying around. Check your repair manual, and it shold show you how to test TPS.
Good luck!!! Race ya!