I have a 97 Expedition that I rarely use. I have a POS honda for my 100 mile drive to work everyday. I used the truck the other day and when I started it up I had a high idle(around 1500-2000)I drove it to work(hondas broke) and the high idle never got any better. Everytime I'd dtop for traffic you can hear and feel the high idle. Any idea what is wrong with my truck? I already tired to clean the MAS and it didnt help.Anyone with any other answers?

 

My dad had a problem like the one you described . It turned out to be a intake gasket leak. I have also heard a vacuum hose leak can cause a problem like you described.

 

I had a very similar problem with my idle at about 900 to 1,000 RPMs. My 5.4 normally idles at about 600 RPMs. I took the truck to the dealer who of course stated that this is a normal condition as the check engine light did not come on (to be fair I think they were just being cautious). I insisted that the check it out as I felt it was a safety concern. As it turns out they changed out the Idle Air Contol Valve (PN YL3Z-9F715-AA). Now the truck is back at about 600 RPM. Note I just read the Service statement and it says they performed an EED Test, Smoke test to chedk for Air Vacuum leaks, PID monitorthen inspec and found the IAC valve sticking open. Hope this helps.