while in park the car is about at 500 rpm if i try to keep it steady any where between the 500 and 1500 rpm the rpm keeps fluctuating it doesn't stay still and lights dim as the rpm drops and brighten as they rise. At stop lights the rpm drops to about 200 rpm for a second and jumps back to normal and sometimes has just turned off completely. could it be a vacuum leak? or the tps? I've changed the spark plugs and cleaned the throttle and the problem continues
