I have a 98 f250 with a 4.6 truck was running great but now when I start it up first thing in the morning or after it has sat for 8 hours it seems to want to stall.. It stumbles for a few seconds then reves upand is good to go.. I'm thing it may be my fuel filter but not sure... any help would be great...

 

I would suspect a sticky IAC valve. (Idle Air Control) This is pretty common on older vehicles with some miles on them.

 

Thanks..could you give me a location on the IAC valve..never had mess around with that before...

 

It's on top of the intake behind the throttlebody. It has a 2 wire plug on it and is held down by (2) 8mm headed bolts.