Expedition Idle problem

[royalet]

I have 1 1998 expo with 82K on it, 5.4L
the problem is idle issues. when started the idle lopes and is rough, i have no problem on accelerating, then th idles raises up in park to about 3K rpm's, and at times when i'm stopping i have to hold my foot down on the brake hard to keep the truck from taking off, My data link is not working for some reason , just trying to see if anyone knows anything before the dealer hits me up. Thanks

 

[PaulC]

Sounds as if you have a vacuum leak somewhere on the engine. The PCV valve plumbing is notorious for cracking and allowing too much air into the engine. This will impact idle quality and speed. If I'm right, this should not be too expensive to fix.

 

[Guest]

I just traded in my 1997 w/ 145k, Expedition Eddie Bauer for a 99 EB. My 1997 had the same problem right before I traded it in. It was the coolant sensor. There are 3 total, you just have to find out which one is bad. Had it replaced and before I traded it in it ran fine.