Jwild909

I'm hoping you guys could help me out.
A few months ago a few buddies and I replaced my master cylinder since my pedal would sink to the floor. That fixed that problem. Recently the pedal takes a lot of force to stop and has a lot of play until you can actually feel the brakes grab. Every now and then I have to drive the car around for a good 20 mins before I get the pressure back up. Well today the pedal actually sat right at the top and with the slightest pressure on the pedal the brakes would grab but that's the first time that has happened. Oh yea I also just had my booster replaced on Friday. Well it still has a lot of play in the brake pedal before it actually grabs so my question to you guys is, could my rear calipers be seized or any caliper for that matter? Could it be something with the hydraulic brake pressure? Any opinions would be great, this has me stumped!