What I found when I went to an aftermarket tb and it was idleing high, (idle was set to 800, was Idleing at 1200). it wasnt hitting the idle screw but the was still gaps around the plate itself. it was installed off center. I loosened the screws that held it to the crossbar giving it some play which allowed it to fully close, then retightened the screws. idle dropped down to where it was supposed to be. there shouldnt be any gaps, thats what the iac valve is for.