[jeffrsmith]

Did you test or replace your thermostat?

If you have a sticking thermostat it can cause the temp to rise higher than normal. Yes, the swing on the temp gauge will happen, but if you are going to three quarters and then it starts to come back down it sound like a sticky thermostat.

Pull the thermostat and test it, if it is not an OEM thermostat replace it - Stant thermostats, when put in a Porsche are junk, they just don't work properly.