[mgchevyparts]

I asked because your problem is similar to calipers hitting the frame on a full lock to lock turn. If a caliper hits, such as on the frame, when the brakes are applied the piston will get knocked in and your pedal goes to the floor, as soon as you pump the pedal the brakes return as the piston moves back outward and refills wih fluid. If this never happened before it's probably related to the hydroboost