I'm a up and coming service tech. Yesterday on my way home my 92 Dodge Dakota starting lossing power only in 5th gear (Man.). On flat roads ill do 55-65 mph top, and 45-50 up hill (drops to 45ish and ill have to downshift to climb a hill, not running 45 in 5th). Today at work we pull my truck in and start checking it out while we had nothing else to work on. Cat's fine, Fuel pressure 32 psi on idle 42 with vacuum pulled (Great), Compression perfect, Timing Perfect, Vacuum Gauge and smoke test turn up no leaks, 5th gear seems to have no issues until it reaches the 2000 rpm range. Everyone is stumped, The master cert tech can only suggest that maybe the timing chain has worn even though timing has not missed a beat still could be worn. Ive also ruled out 5th gear trans problems due to the fact that in 5th it will pull till it reaches the 2000rpm range but will not pull past that, full throttle only gets me to 2000 rpm in 5th.

A little about the truck. 92 Dodge Dakota manual trans V6 3.9 with 230k miles. During our test i found the rear main pinion seal has a slow leak and is on my list of to be fixed soon but we can not see how this could be related. Fuel Filter was replaced just before doing a Fuel pressure test.

Please no smart answer like i got from the service adviser all day, yes the truck is 22 years old, no this does not mean that one day it decided its just to old and rusted to run right and there no other issue then age. (sorry for the little rant, been told all day truck was too old to fix and i was hurting the economy bye trying to fix something that old).