2001 Expedition idling too high
For about the past month my 2001 expedition has been idling too high at times. It doesn't do it all the time. I can always tell when its going to start because the gauges all drop to to the left when I crank the car. Then after it's on, it idles at 2000 rmp while in park. When you put it in reverse or drive it jerks. Sometimes it starts to idle too high while sitting at a stop light. It started yesterday while at a light and when I started to drive and got up to 35 mph the rpm was at 4000. Any idea about what it could be.