Stalling at idle on 2000 Mercury Villager

Changed plugs, cap, rotor, wires and still having idle issues. Runs fine at speed but drops down to 400 rpm or less at idle then back to 650 until engine stalls. I have yet to see a check engine light.

Asked by for the 2000 Mercury Villager
Try cleaning out the idle motor and the throttle body. Make sure there aren't any vacuum leaks.