I'm driving a 94 e420 with approx 90000 miles. The idle has suddenly dropped off to near nothing. Showing about 200 rpm or less. Lights go dim, it is so low. No check engine light but the car will stall if the a/c is on. Does this sound like a sensor that i could change myself? Also the throttle has become very touchy, seems to have no reaction to throttle movement and then suddenly jump. Any ideas guys. Thanks