Another "brake help" thread...

The proportioning valve is adjusted by bleeding the brakes in the proper order- passenger rear, drivers rear, passenger front, drivers front.

It sounds like your rear brakes are dragging and overheating. If it’s both of them, it’s possible that the rear brake hose that goes from the chassis to the axle is partially collapsed internally. That can hold the brakes on.

Get rid of the speed bleeders, they’re awful. As someone that often has to bleed brakes by themselves I have tried them because it seems like a great idea. In practice, those damn things never work right and typically result in a leak or air still trapped in the system.