2003 f250 4x4 5.4triton automatic. Everything is great except…when accelerating at about 45-50mph & 2000-2200rpms and it shifts into last gear or overdrive. As it changes gears and drops rpm’s to about 1500 the engine/trans kind of vibrates or sounds boggish like it doesn’t want to push the weight of vehicle or some sort of compression loss? I’m far from being a mechanic so any help appreciated. Also, it tends to be more subdued when accelerating harder up to higher speeds, it is more so when leveling out at about 50mph. It doesn’t clunk, or grind, or have any other problems shifting except at 45-50 and dropping rpm’s.
No comments at all?
How many miles are on this truck? How often and by what method has the transmission been serviced? Have you checked the trans fluid? In general, what kind of work has the transmission seen? How about everything else? Spark plugs? Wires? Filters?
The first thing to do is figure out whether this is an engine or transmission issue. Do you have any warning lights on the dash? Do you have something like an O/D off button?
Without knowing anything for sure, my own first thought is an issue with the torque converter clutch.