Miata runs at normal temp all the time except going up steep hills then it runs hot how do you fix this?

Avoid hills. :-) Seriously, you may be able to put in a cooler thermostat. There are also better (higher capacity) radiators out there. I've also read that by removing the weatherstrip at the rear of the engine compartment (atop the firewall), underhood temps are greatly reduced. Also, you may want to have the cooling system completely flushed and leak tested by a qualified shop. Your cooling fan is probably going. The bearings are worn and when the car isn't level the fan doesn't sit straight. For now you can drive back down the hill and the fan will fall forward but you will have to replace it. It's only a one hour job but you'll have to buy the whole fan assembly and that a 300ish dollar part. Try flushing the system first, and burping it correctly. It's possible there are air pockets in the system, that are being exploited when the car is under heavy load. The fan may be going, but even so, you should be able to purchase an aftermarket fan for far less that the Mazda Factory price that will work just as well. In some cases, you may just need to splice the power and ground wires from the original harness.