A temperature problem at freeway speeds is almost always a radiator problem.
Seems like you’re the second person with a brand new Griffin cross flow that has cooling issues...
Easy, you changed a broken thermostat for a good one. The thermostat temperature change has no part of it, besides the extra wear and tear you’re putting on your engine running it below ideal temperature.
The thermostat only sets the low temperature. If it effects anything other than the low temp, it’s not operating properly.
