2003 cummins No power!
 

Driving my 03 that has 268000 miles bone stock and i cant get above 65 mph not pullin a trailer. Cruise buries throttle and still no power. Turn cruise off and same result. Just replaced fuel and air filters. Ran perfect yesterday. When it does downshift it just runs up against rev limit, shifts and bogs down again. Nay help is appreciated. THANKS

Sounds like a tranny issue, although I can't help you much on the exact cause I would lean toward TC.

Any codes?
Bands been adjusted?