After bleeding the brakes it drove fine twice. third time im running it i go to hit the brakes and the brake pedal instantly goes hard and the brakes all but lock up for a split second, if i continue to press the brake pedal they act normal for a few pumps. when i come off the pedal for a little bit and push again it goes hard and brakes all but lock up again. wtf? it has a new accumulator that has worked great. thanks in advance