The right rear caliper is dragging, on the highway at normal speed, the rotor, caliper, and even the rim gets super hot! Replaced the caliper and the flex brake line but problem still exists. The other brakes seem to be fine. Any suggestions?

 

Since no one has answered, I will try.
Can you do this, after a short run and the wheel is warm open the caliper bleeder screw a little and see if brake fluid comes out under pressure. If so , there is a restriction in the brake line. Some vehicles have a hose between the caliper and metal brake line. Many times that hose will have come apart inside and block the return of the small amount of brake fluid from the caliper. It doesn't have to be much, but is enough to prevent the caliper piston from retracting.
Also, when replacing calipers always clean the accumulated rust from the mounting so the caliper has room to be free to slide/move. Let us know if you need more suggestions.

 

Make sure the Caliper guide pin is sliding easily in the caliper bracket. The caliper needs to be able to slide back and forth.

 

Hanky and 2ltime, Thank You both for your responses!
Hanky, We did replace the rubber hose, along with the caliper previously, problem remained. And 2ltime, we also neverseised the caliper pins and same result. So, a friend suggested to crack the bleeder valve on the opposite side,[ drivers side rear], with the thinking the portioning valve may have been stuck off center, holding pressure to the passenger side. We did that and also took the caliper back off and and turned the caliper cylinder back in alittle, [the screw in type], and remounted. Took the van for a 45 minute drive on mostly open highway, and some city streets. Not sure which worked, maybe the combination, but, got no heat whatsoever on the brake side in question! Fingers crossed!