When the car is in neutral and u rev the motor, it breaks up. If I try to hold the idle steady it surges. When driving the car, as long as I continue to bring up the rpm it is fine but if I try to hold it steady the car bucks.??? The car used to run fine from the previous owner. However he had a slight fender bender and among all thing went to jail and unfortunatley can't contact to figure out the problem. Car is a 91 dx with 91si swap.