Well, guys.

I can definitely rule out the overflow tank and hose as having a leak or being faulty. The only thing left is head gasket, but I think I can almost rule it out too. I went through some steps from the service manual, including hooking up the tester, pumping to 16 psi and revving in place. Manual says if gasket was perforated, the revving would have caused pressure fluctuation. The needle was rock steady, and rising slowly with heat expansion. Furthermore, I smelled the exhaust and not a hint of coolant. If anything, a little water vapor with the cold weather. Heater core is dry too and there is not a single drip anywhere. Still, the coolant does not seem to be returning from bottle, so it must be losing the vacuum effect somewhere.

I'm totally baffled at this problem. W-T-F? LOL