I'm using the Milidon high flow thermostat that was recommended with the Milidon high volume water pump. I believe the thermostat was rated at 185.These are all good.
I agree about moving water too quickly through the radiator,This is not your current problem. This should not become a problem until much higher rpm but the problem was there using the stock water pump and 180 thermostat.And that's the proof. I've considered putting a stock thermostat back in. Don't do it, the stat sets the minimum water temp, and has nothing to do with controlling an overheat issue unless it sticks closed, and yours obviously is not sticking closed.
The lower hose is not collapsing, it has the coiled wire in it and is firm when the engine is running.Very good
I am running electric Accumeter gauges, but have checked the temps with an IR gun. Yesterday, the upper hose was showing 221 degrees, the lower showing 210 after idling for 15 minutes.You need to shoot the metal intake right below the thermostat and on the way back to the heads. Keyword "metal".
Agreed, the open element air cleaner makes it worse.Open, closed, or not there at, all makes no difference. Stuffing 221* air into an already overheating engine is like,suicide, to the engine.
I've owned this car for 14 years, and thought recently that I had finally turned the corner. At this point, I really don't know what to try other than a different style of fan blade now you're thinking....Larry