Brake Master Cylinder problems of the 2011 Ford F-250

I can not get this soft break to go away! it never had a solid break but I bought it used and figured it needed a break job. I had calipers to start locking up one after the other within a couple days of each other, so I replace them all. Then the new ones started getting hot. So I replace all the break lines and master cylinder. After all that I still have a very soft break, almost as if there is air in the lines. I know air can't be the issue because the break system was bleed using a machine. Now after doing research online I have come across a lot of people talking about this exact issue. This needs to get fixed, there is no way to tell when you are actually having break issue come up because they feel spongy when they are working at there best.

The contact owns a 2011 Ford F-250. While driving at an unknown speed, the brakes failed and the brake pedal traveled to the floor when fully applied. The vehicle was taken to the dealer where it was diagnosed that the brake pads, master cylinder, and abs needed to be replaced. The vehicle was repaired, but the failure persisted. The manufacturer was notified of the failure. The failure mileage was 34,000. The VIN was not available.