I have a problem when my Ford Escort when it is idle. It feels very jumpy like it wants to cut out. I had the Idle air control valve changed on it and also a part that controls the temperature. Yesterday the engine sounded like it was runnning faster than the car was actually going and then it felt like i was losing power in the car and then it rectified itself and was running normally. What could the problem be so that I can take my car to a garage and have the problem fixed.