i have a 2001 ram 2500 cumins diesel. when i am going up a hill, it has a hard time[:@]. it doesn't have as much power as before. anyone know whats worng

 

I had the same problem with my 84 Chevy 6.2 diesel. It ended up being the torque converter.

 

My buddies cummins does the same . I think because they're diesels they don't have the rpm range that gasser's do and that they can't spool their turbo quick enuff . So I think it's probably turbo lag.

 

older style cummins are weak to begin with.. i test drove a 2001 cummins and that thing was a turd taking off and mashing the pedal while cruising.. hell i think my dodge with a 318, with 35's and stock gears is faster then that

 

Go to the dealer and have the computer flashed. Know of a guy who had this problem towing fifth wheel camping trailers, they did something with the computer and he was able to rip up hills with a trailer on.
Get the turbo checked

 

Diesels are built for torque, not horsepower. A TD can haul much more than your 5.9 gasser ever could hope for.

 

Air filter? Fuel Filter? Those are good places to start on a diesel.