I've been trying to resolve a hunting idle issue for about a month now. Last nite I noticed something unusual. Normally when I am working on my car it is parked on a rather flat surface, and the idle issue where the tach needle bounces around from 700 to 500 at two-second intervals when the car is not completely warmed up. However last nite I was parked on a rather steep incline with the front of the car pointing up the incline, and the idle was just as smooth as ever and it didn't bounce around like it normally does. So I backed the car into an area where it would be "level" again (about 15 minutes later, after observing it run just fine with the front elevated) and sure enough it started bouncing around just as it had before.

I've cleaned the throttle body, changed fuel pressure regulator, new plug wires, plugs,.