Good to hear you got your temps under control, Bill.

As an update, I was finally able to backflush the system, I removed the thermostat and flushed it till clear, then refilled with distilled water and MB 325.0 60:40.

Past few days were very hot and I've been using the car a lot to test it.

Temps peak at 100c at the hottest part of the day in the worst of traffic, but most of the time it's at 90 or so. And the AC blows cold even at peak temps in standstill traffic, so I am happy.