Ford

2001 ford expedition idle problems? suv runs excellent except for one thing: after driving the expedition for awhile and warming it up, it will lose power while idling in gear at red lights. it does not stall, however; the engine revs up to get it back at the normal idle. sometimes the idle problem will not occur at a red light, other times it will occur 4-5 times. this does not happen while the vehicle is in park, only when it is in drive. i have replaced the egr valve and cleaned the throttle body plates, but the problem still persists. also, when used at night, the lights inside the vehicle will dim when this idling problem occurs. can anyone help me???

Check your pcv tube where it connects to the back of the throttle body. they have a tendency to rot due to oil contamination over time. this results in a vacuum leak which will cause the erratic idle.