my is doing exactly the same thing. what does yours idle at?
Quote Originally Posted by gregs78cam View Post
At an idle in neutral my Dual TBI the IAC stays on 0 steps. The throttle blades are letting to much air through even while closed ALL the way. It idles where I want so it's not bad. In gear it has some steps and maintains idle fine. I closed off the other IAC in the same way.

Yes IAC and O2 sensor have different threads, O2 is 18mm, IAC is 20mm.