I wanted to put the problem behind me and get on to other things so I bought a new IAC for $110. Idle is consistent now. I suspect my cold start idle problem will also be fixed. Will not know until next winter.
For everyones information. My IAC had proper voltage to it, ohmed out within spec, and did not affect idle when tapping on the housing. Never was able to see the valve move during any tests with the new or old IAC. Apparently it has to be in the vehicle and running for it to actually open and close the valve. Finally figured out that it was not working by unplugging it while the vehicle was running and there was no change in idle speed. With the new IAC the truck almost stalls when you unplug it.
Sometime in the future I'll get around to cleaning the intake better with Deep Creep, but probably not until I decide to change plugs. It's running too good right now to mess with. Would like to enjoy it for a while and get the drivetrain repairs done first.
Last edited by Rob K; 05-10-2010 at 11:14 PM.