For about the last year, I have been noticing a hesitation while driving. It only seems to happen as I am coasting, say down a hill, and then lightly get back on the gas to start up the other side, it will hesitate for a second. It almost feels like the truck is not sure which gear it wants. Also, when I am coasting sometimes it feels like the truck wants to down shift as if there were an engine brake. I am not sure what this could be.

Here is another bit of, maybe, useful information. I had the engine replaced at the dealer about a year ago as well (cam phaser exposion). I do not remember this happening before then. I took it back to the dealer after as I felt the engine was very sluggish and for the hesitation and they told me I had a code for the cat being clogged up (due to the cam phaser and dumping raw gas down the exhaust) and that was most likely causing both problems. I fixed the cat (not at the dealer $$$$$$), but still have both problems. The dealer did have to fix one problem right after the new engine install, some of the vacuum lines were crossed. Could a vacuum line be causing these issues? I still have 2 years of warranty left on the engine, so if it is anythng to due with that, I would like to get it resolved. Thanks.

 

I guess I also should have mentioned, 2004 FX4 with 5.4L 3V