Air Brake Antilock problems of the 2002 Chevrolet S10

-brakes failed to stop vehicle (2002 cherolet S10 pickup) while traveling at low speed (20-35 mph). Brake pedal went to the floor at least once, possibly more, as I tried to get the brakes to engage. Brakes finally caught but on the right side only for the vehicle jerked to the right before it came to a stop. Vehicle, which is still under warrenty, was towed to dealer and no defects or problems were found. Dealer stated that there is nothing they can do to since they cannot replicate problem.