Master Cylinder to blame for my crappy brakes?? HELP

[Kdubslugga]

My brakes are really getting bad, last year before i put it away i changed the rear brakes, drums and everything, also replaced the front brakes. bled the brakes and that work a little, but now it has a lot of air in the brakes. I mash on the brakes and i hear a lot but air. If i sit in gravel with my foot on the brake, it starts to peel out. It feels like im trying to stop a 10,000 lb car when i slam the brakes on. Am i missing anything? do you guys think its the master cylinder? Its looking pretty old and rusty, what else COULD it be??

 

[Mustang5L5]

You prob still have air. How empty did you let the system get? If the MC went dry, you will need to bench bleed it as it's hard to get all the air out while it's in the car since it's at an odd angle.