I bought a 1998 Z71 in February this year , 2022 . 4 days ago driving at 35 mph the truck started braking on its own . I managed to get off the street safely . It was the front brakes . I could not go forward or reverse . After about 30 minutes the brakes worked fine for about half a mile . Pulling in to a friend's driveway the brakes started grabbing on their own . Even after sitting for awhile the truck can only go about 30 feet forward or in reverse before brakes lock . After a couple of hours we jacked the front of the truck up and wheels turned freely. Looking at master cylinder when you pushed on brakes , brake fluid came out of master cylinder . A lot ! Put new master cylinder on . Bled all brakes and abs . Brakes felt great . Crank truck up to test drive and brake pedal goes to floor . And the brakes still brake on their own after 30-40 feet . Have plenty of brakes with truck off . Turn truck on , brake pedal to floor . It still brakes on its own after 30-40 feet . I need Help !