It's hard for some of us to keep up with the facts. It would be better if you could keep all this in one thread somewhere.
Anyway, I think I saw that you recently replaced the degas bottle. If not, then that would be the first place to look.
If you had a gen II, then I would suspect the front and back thermostat housings. Otherwise, check all the plastic pieces, including those in the middle of hoses, and the side tanks on the radiator. Also check every hose connection. Don't just look at them, twist and tug on them. Look closely at the DCCV too.
If you used adjustable hose clamps anywhere, check those extra closely.
You may have to repeat the pressure test when the engine is cold and use a mechanic's stethoscope to listen everywhere to the cooling system until you hear the sounds of escaping air or water somewhere.
