well i have a 96 rs a/t, and when i put my 55mm tb on, i put a new iac motor, and a tps, so i doubt its either of them. i think i have a leak from the intake mani, a mechanic once told me that so im guess thats it, but then what would cause my car to buck like it does, and the weird thing is, if i put it in neutral when stopping instead of drive, when i almost stop, the car while thump, and u can feel it do it too, i think its from the brakes, but who knows? i also put a new engine coolant temperature sensor on, didnt really do much so...14 bucks down the drain