Help troubleshoot front disc brakes sticking

[pokey64]

Just starting to put some miles on our Camaro and are working through the Gremlins. Our latest is that both front disc brakes start to grab/stick after a couple miles of driving. We start to smell burning brake pads and they get scorching hot. If you jack up the front end you have to push pretty hard to spin the wheel. After the car sits for a while the wheels will spin freely again. The brakes feel firm and there is not any play in the peddle.

The setup came with the car and I belive it was from CPP. Everything seams to be pretty new looking.

Heres a list of what I've heard for suggestions so far:
Sticking proportioning valve (I have heard they rarely ever fail, looks pretty new)
Contaminents in the fluid (had a leaking rear line so was just changed by the local shop)
Wrong brake fluid/brake fluid boiling (not sure what they used but had issue before)
Sticking pistons in the calipers (calipers look pretty new)
Inside of hose breaking down and acting as a check valve or collapsing (hoses look pretty new)
Pre-load on the master (I removed the master and checked this one. It looks fine)

The local shop seemed to be grasping at straws and I am not really sure of the right way to troubleshoot the real issue. Where would you guys start?

Here are some pics of the setup.

Thanks!