Having trouble with my motor idling...has anyone had this problem and how did they fix it? At the moment i can't get the engine idle down from 1500rpm. I just changed the throttle body today as there was a leak in the butterfly assembly on the old one but nothing has changed and i can't wind the idle adjustment down any further. Also when i rev it to about 2500rpm and let it go the manifold vibrates harshly at a point in the rev range both on the way up and on the way down. The car is going in for a tune this weekend but we thought the new throttle body would have ironed out a few problems and it hasn't. Has anyone got any ideas?