Do you just have a out of the box t stat or do you add a little bypass help with 3 1/8 holes on the outer edges?
Out of the box Milodon high-flow stat...
I didn't read the entire thread, but I've personally had a "high flow" thermostat cause the coolant to not stay in the radiator long enough to exchange heat with the air. It's nearly the same issue as no thermostat, minimal restriction.
