Trucks runs rough going down the road, rough idle.

Being a Ford tech I see this often. The intake on These trucks is the weakest link and I hate that they went to plastic. The front passenger side of the intake where the metal crossover tube is has an o-ring type gaskets that sits in a recessed groove in the plastic part of the intake and over time the outside edges of this recessed area will warp and crack due to heat and age,therefore the o-ring does not stay in the position that it is meant to and coolant will leak into the plug holes and there is your rough running engine.pull a couple of coils out and see if the bottom of the boots are wet and what I do (but don't suggest it) is touch my tongue on it and see if it has the sweet taste of coolant. If so a new intake is in your future.btw amazon has a good deal on one that is waaaay cheaper than dealer.good luck