1995 dodge losing power

[tat2man67]

i run a 1995 dodge 3500 5.9L diesel. it starts and runs fine, but while going through the gears,(manual tranny), it just doesnt have the power it used to. can run only about 60mph in 5th gear overdrive. i just did a service and changed all the filters. didnt help. the truck used to run 75+ mph. i get the accelrator pedal about half the way down, good power. from half way down to the floor, no change. almost like a governor is on it. any ideas would be very helpful. need truck for work. thx in advance, frank

[BleedDodge]

We had a 6.5 Chevy once that was acting like that, and it was the lift pump. I'm not familiar with the Cummins though.