Issue is that it revs higher then normal but transmission appears to work just fine. No hard 3-4 shift most times. Seems a bit gutless. All fuses appear good. CEL comes on and off (haven't checked codes).

When I got the truck it was low on trans fluid so topped it off. Stunk for a bit like it deglazed the clutches (it was about 5 qts low).

I am not sure where to go first. I had a similar sluggishness on a Crown Vic and that turned out to be clogged cat.

The person I got the truck from said it was a rebuilt engine and trans.