Had a check engine light on my 2001 Ford Windstar, C1518 "Intake Manifold Runner Control Stuck Open." After reading forums, most pointed to a plastic "bushing" clip coming off leaving a control arm hanging loose, leaving the intake manifold hanging open. Found a pack of replacement bushings (Dorman #47099) at O'Reilly Auto and managed to get a new one on with a couple pliers, then reinserted the control arm. Forums say that when this is replaced, the CEL should turn off on its own within a few days (about 60-120 miles of driving). I'll update in comments after a few days of driving. MY FOLLOWUP TO THIS VIDEO: A few days later, the check engine light DID go away on its own. It's difficult to say with certainty, but my van also feels a bit more responsive, especially accelerating to highway speeds. So all in all, a good $6 experiment seems to have paid off!
2001, Ford Windstar, P1518, Intake Manifold Runner Control, Stuck Open, bushing