tried it all
I have a exaust brake, adjusted the shoes, bled the brakes a 1000 times, gravity, pressure, reverse, pump, ive bled them. I put 1500$$$ in brakes- New master, bigger rear cylinders, new RWAL valve, New EGR calipers, slotted roters, shoes, braded lines... . the brakes work but at speed with a little load mush and no stop. I guess the last to try is new vac unit