I have a 1997 f-150 that has stumped me. when my truch has sat for a period of 4 hours or longer it will not idle. I start it and have to keep my foot on the gas to keep it running. once I get it in gear and going it runs like a champ but when I slow down and come to an idle the truck dies. To keep it running I have to keep my feet on the gas and the brake. But after running for about 3 or 4 miles the problem fixes its self, then the next morning or afternoon I have the same problem. If any one has had this problem or some sugestions I would be greatful.

 

the IAC idle air control could be gumbed up. thats the one thing i think of when you have to use the gas to keep a efi motor running.