I have a 2005 f450 with 6.8 v10, I will just explain what all I have done, I bought the truck with these issues thinking of just swapping new motor, but here goes, a high pitch squeeling noise that increases with rpms, it some times doesnt make a noise after driiving for a minute but always comes back, from under what sounds to be driver side valve cover, we took it off hoping to see issue right away, everyhing looks normal a little sludge build up, noise seems to get louder with cover off, but can't tell for sure we have check all belts tensioner, but seems to def be from valve cover area
The motor is extremely powerless. And slow rpm acceleration Can put it to floor and only revs to 3200 rpms wether it's in neutral or driving, won't go about 40mph and it takes a good time to get there, we tried replacing the maf sensor becouse we unplugged it and the trucks wrench light came on and that means it's running in limp mode but it actually made the truck run super well. Instant throttle response and would go over 4kr pms with fast rpm acceleration, so we bought new and plugged all in cleared codes and same problem again, the truck isn't throwing any CEL or dio codes. We are scanning with a Matco Determinator the night I bought it I tried to drive it home while running very poorly, I got about 100 miles and the truck started over heating so I immed pulled over and shut down and towed home it has good coolent and thermastat. But I drove around after trying to fix today and didnt over heat at all even while idleing for long periods of time in the shop. We are at a stand still here and have out mind stumped. Any suggestions?