I can not figure out what is wrong with my car I really can not afford to take it to the shop so I'm trying to see if I can fix it on my own. The car idles on its own with out me doing anything to the car sometimes the service engine light goes on which makes the car jerk. I took it to a shop and was told it was the idle speed control motor. So I bought the part and put it in myself, but the problem still continues. The shop also said it might be the TPS. Can someone help me?