hell you dont need heat in arizona!!!
try NE OHIO...its -16 wind chill right now with no end in site!!!! might try a hotter 'stat-maybe a 195* seems like you covered everything else
6. After running engine, upper radiator hose is hot and lower hose is luke warm.
after rereading your post i noticed this statement...if i am thinking right the lower hose should be hot and upper COOL till thermostat opens...this tells me its too cool of a stat or stat isnt working as it should even though you "bench tested" it...good luck and let us know what you find!!!