Later tonight i went back to the shop with some new test i had in my head, i
found coolant in #3, plug was wet like hell. A leak down resulted in a climb
of 8 psi in the coolant pressure tester.

Do you get that? Injecting compress air into the suspicious cylinder wile
the coolant system was pump to 10 psi made the coolant tester gauge climb to
18 PSI, even more.

Reverse situation...

I'm perplex about those test, i can't inject air into the cylinder (lost of
pressure on the coolant pressure test #1) but i can do the opposite, of
course the leak down as more pressure than the coolant tester pump.

So yes, what we have here is a deteriorated head gasket.

Ben