My brake pedal has not been holding pressure (I'm also having issues w/boost) so I've been trying to find a vaccum leak. I couldn't find one, but I took some stuff off and plugged some vacuum hoses. One of the plugs came out and I was at about 10 in vacuum. For some reason when I had the leak the brake pedal held the pressure and didn't fall to the floor. When I fixed the leak (22 in vacuum)and took it for a drive again the pedal falls to the floor again. WTF?

I'm pretty sure the brake MC is not that old (Autozone replacement). What else could be the cause? I'm also not getting much boost...at all.