Trouble with unstable idle when placed in gear and especially with AC on. I've tried to find that elusive sweet spot between an unacceptably high idle at rest and a low or stalled rpm when in gear and with AC on. No Vacuum leaks found.

What I would like to understand is why we wouldn't adjust idle using the throttle body screw that sets the opening of the throttle. I know the spec says 0.002 gap, but if I'm stalling, wouldn't it help to open that up a little? And since they're both past the manifold exhaust setting, can someone tell me why it would matter which one is allowing more air into the system?