You need to replace the thermostat, which is rated at 105C. When you remove the plug to the stat, check for corrosion of the pins. Coolant eventually leaks out of the connection point on the stat, and will, given time, follow the harness by capilliary action all the way back to the e box, to do even more damage. Sounds improbable, but it happens.
You won't notice any difference under normal conditions when the job is done, as the purpose of the system is to open the stat more under very high ambient temperatures, or high engine loads. This why it gets missed or ignored