my corolla has an integral iac within the throttle body .well i took it apart to clean it it has three small screws and plate that come off then a i guess an adjuster inside that i unscrewed and didn’t realize the threads inside don’t have a stop point.so now when i start it it idles at 2000 plus and takes awhile to come down.if i put it in gear it will go down to where it’s supposed to be .the reason i took it apart was it had the toyota stalling problem were it vibrated bad lost power then died.i saw a post where the fix was to turn the screw recessed on the tb a turn out and fixed it.
There is a screw on the throttle body, but its function is to keep the throttle plate from damaging the bore of the throttle body. This is not meant to be adjusted. You just screw it in until it makes contact. If you go too far, then the TPS (throttle position sensor) will be off the zero position and computer will then think your foot is on the gas and it will not attempt to control the idle speed.