Truck doesn’t like hills

[Bassmedic46]

Thinking about buying a 2001 Dodge Ram with the 5.9 engine. The person says it doesn’t like hills but needs a tuneup. Would a tuneup fix the issue or could it be the catalytic converter?

 

[Fast69Mopar]

It could be a number of things. It could be down on power from needing a major tune up with plugs, wires, cap and rotor or it could be a transmission issue like the trans is not downshifting from 4th to 3rd or 3rd to 2nd when trying to accelerate uphill. Dont panic at the issue though. A test drive would be a huge help in determining what is going on.

 

[El Huapo]

Add to the correct prior reply by Fast69Mopar, fuel supply. A partially-clogged fuel filter or weak fuel pump can cause problems that don't show up until you ask for more power (meaning more fuel). The fuel pressure test at idle or no-load may show good, but climbing a hill requires more volume than sitting still.
This reply is a little late, but I wonder---did you get the truck? Did you solve the "hill" problem?