I have a new IAC to put on and it came with a new gasket. Do I need to change the gasket if the old one is still in good condition, not torn. And if so, is there any glue, oil or sealant that should be used between the throttle body or the iac body?
I've reused my old gasket quite a few times. As long as there are no tears on it and it's not brittle, you can reuse it. I like to use a little bit of gasket adhesive or some vaseline though.