For about 6 months or so when ya start my 06 e250 with a 5.4,there's no fast idle.It runs a bit rough then after 5 mins or so it's back to normal.There are no codes,which means i need to get it to my reg wrench which is getting more challenging cause he's a small shop that is getting a good rep and he can't just get me in and out anymore.I do the maintance oil changes,fuel filters,ect.My guess is some kinda high idle sensor or relay or the throttle control unit whatever it's called that replaced the old linkages may be carboned up,the van has 550,000 with alot of idling.When you start it after its warm it's fine it's just in situations were you would have the high idle kick on like overnight.
