2004 F-150 engine issues
 

I have a 2004 F150 xlt 4x4(not fx4), 5.4 with 140,000 miles.

Up to about 100,000 the truck was flawless. at 115,000 i was having some transmission issues. took it to a mechanic and he said i needed new plugs, they were overdue for change so i had them done. still had tranny issues which resulted in a rebuild. #7 ball check wore out and ended up killing the torque converter.

after the tranny was rebuilt the truck seemed to really lack power, which i blamed on a bad rebuild. months later the engine starts ticking and i end up having the cam phaser replaced along with the lifters on that side.

so, after all that along with a couple incidental items; alternator, wheel bearing, etc. I still dont seem to have the power i should. the truck originally would get around 16 - 16.5 mpg (i drive mostly highway) but after the work was getting 14 - 14.5 and this last tank was 13.5.

I have put new boots on the plugs, cleaned the maf and throttle body.

WHAT SHOULD I DO NEXT. i have taken it back to the dealer, who says everything seems fine, but i know how it shoud feel. I can't believe that a truck of this quality should not last more than 140,000 highway miles.

Any help would be greatly appreciated.

Can you feel the truck shifting into overdrive? Can you feel the torque converter locking up as its supposed to ? Can you take it out of overdrive with the button on the shift lever?