I have a 1997 Mercury Villager i brought it to a shop they put it on a machine the machine said it needed 3 sensors 2 oxygen and 1 mass airflow sensor i replaced all of them and it still runs the same. when u start it up it runs really good. after it warms up it starts jerking really bad and starts popping could u please tell me whats wrong. my email is Customer (name blocked for privacy)@yahoo.com