Another Brake Problem Thread

[68 P.O.S.]

So, I just did a complete brake job on my truck and I cannot get a decent pedal. I'm in a time crunch since I need the truck for work in the morning, so I'm searching for threads as well. Anyway, for the front I replaced the rotors, calipers, pads, and hoses. For the rear I replaced the drums, shoes, all hardware, and the hose as well. The brakes were gravity bled and I called it good. Got a great pedal right off the bat, then, as soon as I started the truck, it went away. Test drove it and pedal goes to the floor and the truck stops slowly. Replaced master cylinder, bled system, and same result. I've bled the system 3 times and no change. I get a nice high pedal each time, then it goes away when I start the truck. Any advice, except for "use the search", is greatly appreciated.