front brakes are locking up after a few miles. what could it be? on 2005 Chevrolet Colorado

we have replaced brake booster, master cylinder and all also has been bled.

1 answer
Really hard to say without looking at the vehicle in person, but one thing that usually causes that is contaminated brake fluid. If somebody put anything other than DOT 3 or DOT 4 brake fluid in your master cylinder, the fluid can become contaminated and cause the rubber seals to swell up.