Please help! Our Dodge 3500 4x4 dsl. has a real brake problem. While driving down the road, it starts having some resistance to excelleration. The it completely locks up all 4 brakes. You can keep excellerating only to come to a complete stop. If you loosen the brake line back to master cylinder and let it squirt fluid for a second, it'll let the pressure off for the time being. But it'll do it all again in 1 mile or 100 miles! We have replaced several blown master cylinders and even tried replacing the hydro-booster. Still no cure. It also has new calipers and pads. Could it be someithng in the ABS system?