Doesn't seem to have been the thermostat.
I'm going to make sure all the air is out of the system, then it goes to a shop for diagnosis/likely water pump.
Thanks!
~M
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'92 Pearl White LS-L Touring SOLD
4.44 Swap, trans cooler, trans filter, trans temp gauge
Color-matched rear body and spoiler, X-drilled and slotted rotors, Axis pads, s/s lines
Raxles front axles