You say the pedal gets harder to push down? Whatever releases the pressure when you let off on the brake is the problem. I think that is controlled through the MC. Last thing messed with is the first thing that is bad. (jbriggs theory of aircraft maintenance)

 

Well the pedal doesn't get harder as you push down, the pedal feel gets firmer every time I brake to the point where the pedal wont go in more than a 1/4 of an inch or so. By this time there is extreme pressure on the whole braking system.

Its very odd, like the brake fluid in the caliper and lines has expanded to put pressure on the pistons in the caliper causing them to squeeze the rotors and putting pressure inside the MC causing the brake pedal to be very firm. Its very odd and doesn't start happening until the car/brakes warm up. I can drive 2-3 miles in the morning before it starts to happen but then they firm up quick as I'm pulling into work but haven't locked up yet.

 

So are the brakes locking up? Or is it just the pedal? I still think its your MC. See if yo can pull it off and get it tested. Don't know where you could take it. A hydraulic shop maybe.

 

The brakes build up to the point where they are just about locked up. Kinda like having a line lock on when drag racing. Then I pull over and what a while, 10 mins, then pressure releases and I can drive for a couple miles. I'm sure its the MC now since everything else was fine before except the old MC was leaking. Because this MC was brand new I figured maybe the booster was bad also. That happened on my 95 Chevy 1500 before, a leaky MC ruined the booster also but in that situation the pedal was very soft.

I'll go thru everything again this weekend.