210° @ Cruise and 180° @ Stop? What's Going On?

Put the hood seal on if it's missing for sure. IMO though, that will not make the difference. You are talking about running 30* hotter going down the road at highway speed. Stick your head out the window. That's a LOT of air flow and your head has way less surface area than the front of your car. The air flow is sufficient, IMO. You need more water flow.