Calipers was a good first-guess. Didn't fix it, though. Time to investigate the steering and suspension--including control arm bushings, ball joints, steering linkage, etc.
Brake gets hot when driving? Time to disassemble, clean, inspect, and repack the wheel bearings.
Brake hoses have a bad reputation for becoming one-way valves. I've never seen it in real life. I've seen multiple brake hoses that just plugged--no flow either direction. NEVER seen one that allowed fluid one way, prevented return the other way. But I suppose there's always a first time.
Have you flushed the brake fluid? Fluid is virgin-clean from reservoir to wheel cylinder, including the RWAL?
The bad news is that you've probably got JB/JN3 brakes. Check the sticker in the glove box to confirm. The worst power brakes ever installed on a GMT400. Consider upgrading the brakes.