2004 chevy express 3500 140k miles automatic trans

I just put on new rear rotors and pads, the calipers seemed fine so left them, though the pistons on one side seemed to be more difficult to push back in.

I was driving up a relatively small hill last night when it suddenly felt like I was driving on mud and the engine kind of stalled and then jumped, and then I coasted to flat ground, turned off the engine. This was about 20 miles after installing the new pads and rotors.

The rear diff fluid is also full and in good condition.

I noticed the side with the stuckish caliper piston was pretty hot - is it possible the piston was stuck in a braking position, heated the relative components enough to swell and create enough resistance that it affected the drivetrain performance?

I’m about to get started working on it for the day and am curious if there’s anything else beyond calipers (they were pretty rough so I’m just replacing them) I should be looking into?