Sorry, but I had this posted in the 2nd Gen yesterday and was hoping some other eyes might see this.

Having an issue with a high brake pedal and dragging brakes. They act like I have my foot lightly on the brake pedal but I don't.
I backed off the adjusters on the rears which helped there but the last time I drove the truck on the freeway both front brakes were dragging and hot( smelling like burning brakes) when I got home.
I did a search and can't find an answer.
Some mention rubber brake hoses closing up, but mine seem to be happening on all four wheels at the same time.
Master cylinder?
Hydraulic brake booster? Is there a check valve on the Hydraulic systems?
*After looking through the repair manual it says possible "blocked master cylinder return port" or "faulty power booster(binds-does not release)"
Is the M/S return port integrated into the M/S body?
Checked for seized caliper pistons and the next morning the wheels spin freely
I've been noticing recently that the pedal height changes between normal to very high while driving around and depressing the brake pedal.
I'm going to try replacing the master cylinder this morning. If anyone has an idea please speak up.

Thanks, Scott

 

Only thing that comes to mind is the rod from the brake linkage to the back of the booster is too long.
Only problem is this doesn't usually happen unless parts have been replaced.

Assume your caliper pins are lubed and not binding.

 

I know this seems simple but have you bled the brakes. Any air in the system will cause the condition of the brakes dragging.

 

I did do the GM wheel cylinders and bled them then a couple of months ago.
Could be related.
Thanks for the idea!