My car idles rock solid at 650 (640-660 according to SAFC-II) when the car is cold. At normal operating temp, it begins to go up and down. Like, it drops down, and starts to die, then goes up to 800, then back down to 500, then up to 800. I have tried adjusting the screw on the top of the throttle body when the car is warmed up, but it doesn't seem to do anything. I screw it all the way in, and nothing happens, all the way out, nothing. When I pulled the screw all the way out, there was black stuff on the end of it. Could this hole be clogged?

Any info is great. Thanks!

 

It's probably plugged up. The air bypass screw should always do something when you adjust it. Clean it out, and check your TPS. Bouncy idle is almost always because it is no longer giving proper resistance values. Consider replacing it if you can't adjust the problem away.

 

Thanks! I will clean it out and adjust properly. TPS resistance does fluxuate a lot when warm, checked with DMM and Analog MM.