Another thing I would like to try b/4 I put a IAC on, I want to start it with the 4wd engaged. I think the actuator leaks vacuum and it idles a bit slower and more rough when in 4 wheel. If it starts and doesn't idle, shift out of 4 wheel and try again. A good size vacuum leak might overcome the slow idle/cold and the IAC can't compensate. It might save me $40 and a unnecessary part. I haven't had the issue until I started using the 4 wheel drive a couple weeks ago. Just thinking out loud.