Hello. New here. I tried searching but couldn't find an answer to this particular problem.

As I drive this truck, especially around town with frequent stops, the brakes will eventually lock up and make the truck unmovable. After a couple hours they release enough that I can load it load it on a trailer although they're still dragging a bit. Then after a day or so, they are fully released and free again.

Master cylinder was replaced in 2013 then the truck sat for a few years. Had some restoration work done on the body/interior that took a couple years and the truck wasn't driven. Finally got to driving it last summer when this started happening. Midas replaced all 4 wheel cylinders...had the same problem. A different shop just replaced the two front rubber hoses....still have the same problem. Hand brake works and seems to release. Seems to have proper free play in the pedal. With the truck on jack stands all 4 wheels are free spinning....Pump the brakes a few times and I can feel just a bit of pressure build in the pedal, and all 4 wheels then have a definite drag to them.

Leaning towards replacing the master cylinder again, or is this a situation of the drums not being set too tight to start with. They spin free, but do they need a couple extra clicks out?

I've got this scheduled to go into a different shop in a few weeks. This shop is much more familiar with older cars/trucks/hot rods so I'm hoping they can pinpoint the problem. Any help resolving this before then would be appreciated.