I am having a problem with air getting into my brakes. I did an SN95 5 lug disc brake conversion, and here is what is happening. Without any warning, my pedal with go to the floor. When I first bleed the brakes, I get a nice firm pedal that allows me to stop on a dime. As time goes on, I lose pressure. I have not bled the brakes in about 9 months, so it is not a fast problem. When I do bleed them, I get air coming out of my passenger front line only. The rears and driver fronts are air free. I had to use a special adapter to fit the 99 Mustang dual piston caliper to fit onto my hard line but no fluid is leaking that I can see. I am just trying to figure out how air is entering my system. Anyone know of ways air can enter the system and cause my brakes to become spongy and them go to the floor? When the pedal goes to the floor, I have to pump it up to build pressure, but as soon as I drive more than 5 feet, I get mushy brakes again. I do have an adjustable proportioning valve if that helps. This sucks, I do not want to lose brakes when I need to make a panic stop in traffic.