After driving approximately 10/15 freeway miles my brakes dragg… enough that I need to downshift and punch it to keep up… when I reach my destination I smell brakes… after sitting a few hours it goes back to normal…was happening once or twice a month… now every trip… I’ve replaced all pads. Booster check valve and just purchased front calipers…
Replace ALL the rubber hoses in your brake system. This is a problem with old rubber brake hoses, especially from GM. They fail internally and act like a check valve to hold pressure against the brakes.
It could also be a master cylinder but replace the hoses anyway as they will become a problem.
By driving under this condition, your rotor(s) may have overheated. After repairs are made, if you feel a vibration while braking you may need to replace a rotor.