Well put. I'd be willing to bet that the problem is your driving style rather than your cooling system. I'm usually not one to to back seat drive, especially from my computer desk, but seriously, slow down. You're only hurting your car if you don't.

As for your 85C at idle and 90C driving, I'd say these are perfectly normal. The factory service manual says that the operating temperature of these cars is supposed to be something like 80-90C.

Also, the factory manual says a 55/45 mix of 55% water 45% coolant, not the other way around.