Rex,

I am in the same boat and have been since the beginning of last season. I have replaced almost everything! New calipers, MC (<-3), lines, caliper brackets, etc. Enough to drive you insane!

I replaced the booster with another one, but it was from the junkyard. After talking with a fellow racer (pro-7 guy) who had been hunting down the same problem and also replacing EVERYTHING, he found that it was the booster.

My car stops fine as well, but has this long/soft pedal and I hate it!. I am going to replace the booster and perhaps you should try the same.

It is very easy to do. First, unbolt the MC from the booster (undo all lines to master and get the MC out of the engine bay) along with the proportioning valve. Second, pull out the pin that connects the pedal to the pushrod. Then there are 4 nuts that go through the firewall (from outside in), remove them (12 or 14 mil). THe booster is now free and ready to come out. It will have some sealant on it making it a bit tough to break free from the firewall, but it will come off.
Reverse the process and you are done!

Remember to always bench bleed a new MC before installing also.

Hope this helps. For both of us...