O.K. guys........I have an 04 f-250 5.4 sd....30,000 miles. About a month ago, I noticed a "stumble" or slight "bucking" while going 55 or so. then, coming to a stop, it will idle super low. But not every time! I have dropped tank,cleaned tank and blew out lines......replaced burnt out exhaust manifold.....replaced plugs coils and intake manifold.........replaced maf sensor......replaced idle air controller......problem is still there. I have hooked up, and watched while driving, fuel pressure tester....fine. I have done a smoke tst, and used propane, and carb cleaner to find any vacuum leaks.....I had two people hook up their code readers(nice, 10,000$+ machines) and can get all kinds of info, but the fact remains, both banks are throwing lean codes. Would camshaft pos. sensor do this, or how about throttle pos. sensor? All logical options have been explored. I do have an issue with my hub lockout on driver's side, but would this create a vaccum leak, if it is bad? I know they use vacuum to engage and disengage, but not sure if that is the issue. it likes to try to pop into 4x4 while driving, like it is full of rust, and does'nt really disengage completely. I'm so lost with this issue!

 

If possible can you post some of the scan data you obtained like fuel trim, O2 readings,rpm, tps etc. ? Shooting from the hip here can get expensive and accomplish little.

 

I have a buddy of mine that has an '05 that had a problem that sounds very similar to yours. After a very long search it turned out to be two separate vacuum leaks under the dash leading to all of the heater vents and such. For your sake I hope it isn't the same thing because we had to rip out his entire dash console, but it might be something you could look into. Let us know what ya find.