I've put approximate 10-20 000km on my truck since I got it, the truck has been pretty much doing this since I picked it up off the lot used.

It's a 2006 F150 XLT w/ 4.6L V8.

On acceleration, I can feel a slight, very slight, vibration in the gas pedal...

Transmission, brakes? The vibration seems to be humming to the sound of the engine accelerating. Could it be a shot motor mount?

I've driven two different 5.4L and there is no similar vibration.

 

You sure it's not missing? How many miles/km are on the truck? It might need spark plugs.

 

Spark plugs have been done within 10 000km. I doubt it's missing, it runs fine, accelerates hard.

 

Its rather well known the modular fords are picky about plugs. which did you use?

 

OEM motorcraft

 

I would bet that you have a miss on one of the cyls. I had the same thing and found coolant in number 4 sparkplug hole. It was dripping from the heater connection directly above the plug. Yours may be from a different reason but sounds like a miss to me. Good luck.

 

**** whatever happened to cylinder miss fire CEL's.

 

A low grade misfire isn't enough to trip a CEL. It pretty much has to be a constant miss.

 

it comes and goes, hasn't been around the last two days.