The problem is in your gear ratio. If you notice that it seems like you are up against a brick wall and then all of a sudden when the RPM's get to a certain point it is like someone turned on the light. I experienced the same problem and it turned out to be the rearend gearing. Too much highway high end and not enough low end power/torque.

My surprise here though is that you even notice it with the 5.4L. I can understand us 4.2L guys, but the V-8 should not be noticeable.

 

only problem with that is that it just started happening all of a sudden and doesnt do it till the engine gets over 140.....good theory but idk bout all that! I took it to the ford dealership today and they checked it like 3 times 2 hours of looking and cant figure it out

 

after the truck gets good and hot take a look underneath and see if the cats are getting hot. If they are clogged they will likely be glowing red. Thats what I suspect.

 

Mine isnt giving me any codes. I have sunk a lot off money into mine to get a little better gas mpg . but it doesnt help when it lugs behind and i have to put my foot into it just to make it go. i thought it was my a/c pulling power nut when i cut the a/c off it still does it. Really wish someone could help

 

Me too man!!! I love my truck but if i dont find a fix soon, its hitting the highway and im going to the dodge forums lol