Loss of power going uphill

I lose power in my 97 Plymouth Breeze when driving up hills. Drives fine everywhere else but I lose power going uphill. Replaced the plugs and wires. No help.Any suggestions???

When was the last time the fuel filter was replaced?

If you don’t know or can’t remember that’s what I’d try next.

Tester

If it’s not a fuel pressure problem due to the filter or pump then you might consider a worn engine or partially clogged converter.

With the plugs out I always run a compression test to make sure the engine I’m working on is mechanically solid.
A vacuum gauge can be used to check for clogged exhaust, etc.