I have a 99 F150 5.4L with 119k miles on it. Its a great truck other then being a gas hog (13.5 on a good day). I notice there is a slight almost like miss at idle. It has new plugs ( no there not bosch) and two new COP's I already had the great blown plug out of the engine issue fixed. I was wondering what you guys think it may be. It doesnt run rough at all, or seem like theres a miss once driving it. It just seems like a slight vibration (miss) at idle. I had a 97 4.6L and I never had a vibration like this with that tuck

 

At that mileage it may be time for a full tune up, first check your IAC, then go through other typical maintenance:
Fuel System Cleaning
PCV valve
Tranny Flush

Optional:
Check EGRs and O2's

good luck

 

good point, with a fuel system cleaning what does that consist of? I just ran a bottle of lucas through the fuel tank a few weeks ago.

 

good point, with a fuel system cleaning what does that consist of? I just ran a bottle of lucas through the fuel tank a few weeks ago...what else do I need to do? BTW how do I change the fuel filter, and what brand should I get?

 

I would just get a filter that is of a reputable name. There are instructions under the technicle articles link at the top of this site for replacing it.

 

if you go to the tech articles part of this tab I think it says there, there's another one with pics listed on one of the other linked f150 sites, I just threw a fram on there, I know I'll get railed for using cheap parts, but whatever. Lucas, although a great product that my whole family can swear by, will not do the same thing as either cleaning the TB yourself or taking it somewhere and spending $90 for a cleaning where they hook up to your fuel rail.