Today I was drive down the highway cruise set at 65, out of nowhere every hill I got to (even the slightest) it would either drop to 60 or 55, and stop there, never inbetween those speeds just those. This has never happened before.

 

Mine does pretty much the same thing. Set the cruise at 70, and it will slow to 60-65 going up hills. It simply will NOT downshift either......

What tire size, and gears ya got?

 

you might have a vac leak in the rubber hose on the cruise line. when it starts leaking, it won't hold speed.

cruise module is under the battery tray. on a jeep you have to remove the battery and tray. i'm not sure if you have to remove all this on a ram or not.

edit - then again - our trucks can be real pigs, and can't climb a hill worth a crap. also, the TPS figures into this, and a bad TPS won't accelerate up a hill with only moderate gas pedal pressure.