Aha! But this is a totally different scenario. Come, Watson, come. The game is afoot!
Firstly, let me say that I think the temperature (assuming a good gauge reading which means a good temperature sending unit) should *always* be at half staff, never higher, once reaching operating temperature.
So, with your symptom of higher temperature under higher heat load (higher engine *and* chassis speeds) I would suspect either a restricted cooling system due to past corrosion blockage or a substandard water-pump (why *do* they insist on calling it a water pump?).
My course of action, based on Yankee frugality, would first off be to do an aggressive cooling system back flush and refill with *good* *quality*
*coolant*. While you are at it - throw a thermostat in. They're cheap enough...If that don't fix her, drain the coolant and retain it for reuse. Next step is to go for the water pump. While it is off, get a gander at the state of the things inside the block. This will require an inspection mirror and good flashlight to even see a thing up there, but what we are looking for is excessive deposits inside the water jacket that might indicate there are other restrictions in the smaller passages. This would be far more likely for you cheapskates out there using the Pres tone brand coolant in your SAABs...
-Fred W