brake issues on a vette

[WS6]

Ok guys I am pulling my hair out over this. I have a z07 vette here at the shop that is giving me worlds of trouble with the brakes. The Z07 cars had 13in front brakes. The pedal went soft on this car so I figured the MC was shot internally. It also was pushing very little fluid out the calipers when bleeding. However, with the new remanned MC the issue is still there and actually worse now. I have bench bled this thing twice for a very long time to ensure all the bubbles where gone. When bleeding the rear calipers, the pedal remains what has been considered firm for now with every pump and bleed. Once we went to the front calipers we would get one bleed out of the front and then the pedal was dead. If we let the car sit for a few minutes then come back, the pedal feels back to it's currently normal self. To me this is saying there is air in the system, but no matter how much I bleed no air comes out. I have pressure bled the system and regular old pump a few times then bleed method. Nothing is working to get this pedal firm. What am I missing here? There are no leaks, the pads are brand new, the rotors are with in spec. I am not seeing any issues with the hoses. The car even with the pedal feeling like crap stops fine and will engage ABS. However, the pedal did not feel like this before it went soft which is what prompted me to replace the MC in the first place.



Thanks guys