Bad master or booster
We bled brakes on my brothers 92 W250 Cummins Ram and he drove it and was able to lock up brakes, it stopped fairly well. After a bit he drove it again and I drove it as well. If you have to stop suddenly brake pedal goes 3/4 to the floor before it starts applying brakes, almost like theres air in the system. There was no air when we bled it. Also when pumping brake pedal with engine off, pedal does not pump up, almost like there's too much freeplay. Does this indicate bad master cylinder?