first of all, thank you so much to all of you on here! I have been using this site for some time now to help me with issues I cant resolve on my own. I really can not say thank you enough.

now about the truck, I work for a fleet maintenance department so this is not a truck I drive every day. unfortunately I only get it when its got an issue. it is a 2004 F150 with the 5.4 motor. 110,000 miles, no aftermarket modifications.

now the issue. truck came in for a stumbling concern, found on cold start up runs good but as it gets warmer it begins to run rough at idle, and gets worse the warmer it gets. off idle it is good till about 1700 rpm where it stumbles severely. but above that to WOT it runs fine. the ONLY code that ever pops up is P0174, lean on bank 2 and my fuel trim on bank 2 is between 17-23. bank 1 fuel trim is between -4 and +4. so bank 1 is running perfect

now what has been replaced.... this truck has had a lot of things done chasing the issue, here goes, new motor craft spark plugs, new MAF, new intake gaskets, new cat converters, new plug boots, new o2 sensors, new fuel filter, new fuel pressure regulator, and I have also swapped all injectors and coils to the opposite bank with absolutely no change. checked elbows on back of intake for cracks, none found, and I have checked all vacuum hoses for leaks, none found. cleaned throttle body, and new TP sensor. compression test showed 155-165 across all 8 cyl.

I am completely out of ideas, my only thought left is it may be a timing issue. I removed the left bank valve cover and the chain didn't seem to have much slack. please if anybody has anything to add I would seriously appreciate it!!