Any idea why my front disc brakes are holding pressure?

[Maximus]

Here is my setup... 1955 2nd Series pickup
eBay bought (dont hammer me) booster/MC kit with bracket for under floor install.
I have front stock disc brakes from the 1978 Firebird that the subframe I used was from. the rears are the same car's rear drums that were on the 10-bolt diff. that came out of the firebird.

I dont have a distribution block/combination valve or proportioning valve but I do have a 10 lb valve on the rear drums.

I had a 2lb valve up front but because of the sticking I removed it, but the sticking stays. Its only after like a mile of driving that they start to stick...
If i either of the front calipers it frees up. and after its free if i push the brakes, they release as they should.

I thought the combination valves just reduce flow to the rear drums, and thus not being connected to my pressure buildup up front.

When i put the chassis together 5 years ago I put new calipers on, so I wouldnt think its the calipers, that and if it was I would only suspect one of the calipers to have failed, not both...
That and in the last 5 years the truck just sat with plumbed brakes and they were maybe pressed 10 times?? I just finally started driving the truck within the last two weeks, around the block and such working out kinks... and then i ran into this on...

Ill try to answer any questions that may help you guys brainstorm, but I am stumped at the moment. The only thing I have left to check is to see if for some reason there is too much fluid in the MC and its somehow building pressure with nowhere to go...

any other ideas?

thanks!

Any suggestions will be considered...