Weird Brake Issue

[TheBrewery]

So I did a front disc conversion from POL I could never get the rears to bleed, it seemed like the old wheel cylinders had locked up... but I could drive it no problem and the fronts worked great. At this time I was planning on going with a hot cam so I would not have any vacuum so I added a vacuum pump for the booster.


So cut to this week and I had swapped out the rear cylinders:

The Good: Bled the brakes and I am getting good flow out of all four corners.

The Bad: The Pedal is not retuning to the top, if I turn the vacuum pump on I loose all pedal pressure and it goes to the floor so I would assume there is air in the lines, right? Bled it again, no air just a good bit of fluid. The issue persists.

Testing procedures: If I pump the brakes it will build pressure(again typical of Air in the line, but wait) with them fully pumped and the pedal very firm I turn on the vacuum pump and the second it kicks on all the pressure is gone, however if I leave the vacuum pump off then pedal pressure holds for over 10 hours which if there was air it would decompress and push the fluid back into the MC but it still holds so I have no clue what is going on now. Also when driving it (short distance and low speed) it will lock up the rears but seems like it does nothing on the front. I put it up on jack stands to make sure the fronts are clamping and they are with very little pedal movement.

Next I am going to check the clearance between the Booster rod and the MC to make sure it's adjusted properly. I am also going to use a reverse bleeder to make double sure there is no air in the lines(I really don't think there is, but I could be wrong). The only other thought is that maybe the Booster has failed and the vent in between the two chambers is not equalizing the vacuum and pulling the rod into the MC causing a gap between the pedal push rod and the back part of the booster. I am totally stumped, help please