Truck came to me with no brakes. Fluid in Master cylinder black, right rear had nothing behind the drum, someone put screw in breakline and screwed back into wheel cylinder to prevent leak. front calipers bleeder rusted off. I replaced both front calipers/pads and rubber brake lines, Replaced entire rear brake assembly and brake line from master cylinder to right front wheel. while bleeding brakes noticed only the front reservoir in master cylinder was going down. test drove and still had air. Bled Master cylinder and got rear reservoir working. During test drive 1st press of pedal will stop truck fairly quickly but pedal fades to floor. if i pump pedal just once or twice b4 stop force applied the have solid pedal and much faster stop. Also both brake an ABS lights are on. I'm leaning 2ward bad master cylinder but Any ideas would be greatly appreciated. thank you in advance