I'm with Jeff66. I've fought this issue on a couple cars. My caliper brackets weren't square with the rotors and my brake pedal did just as you described. You could plug the line going to your front brakes to see if this improves your pedal. I also have used framing squares on the rotor and bracket ears to see how far off the brackets are, it was obvious on mine. There have been other threads on this. See nova404's photobucket and you'll see my picture that resolved my issue.