Working on a 1999 k2500 with the classic body style.
Front brake pads and rotors were just replaced a week ago and almost immediately I noticed the issue.
Brakes work fine except for when i am slowing down and reach 10mph a pulsating type noise comes from drivers side front and pedal pulsates and it feels like drivers side brake releases as truck pulls to the passenger side.
I have looked at pads and rotors and there is a very slight grove in outside pad and outside of rotor on drivers side. There is no debris i can see or feel causing this. I have retightened all bolts to factor torque specs and made sure caliper bolts were able to move as needed and were not in contact with rotor. Also all brakes have been flushed and there is no air in system. Problem is still occurring and I am at a loss. If anyone has info I would greatly appreciate it. Thank you.

 

Sounds like an ABS problem. Try removing the wheel sensors and cleaning them. If the problem is still there then will probably need to replace the sensors and hope it is not the ABS unit itself.