I have a 2004 chevy blazer zr2 with 4 wheel disc brakes, abs, the 4.3l engine, and 45000 miles. Last week I changed out the rear pads and had the rear rotors turned. The front are still original. After this work my blazer now surges when I moderately brake at slower speeds (20mph & under), (feels like they are grabbing and slipping) until I come to a stop. The problem is not as noticable when I brake harder at slower speeds ( 20mph & under) but very noticeable when braking hard at higher speeds (50 mph & up). Would the problem be a bad machining job on the rear rotors, are the fronts warped and now more noticeable with the rears ok, or is there something special about bleeding the brakes with abs? Any help would be greatley appreciated.