I am having problems with the temp going up in my 04 gtp. A few months ago it was overheating so I took it to the shop and they put a new fan motor in it. It runs normal temp untill it sits and idles. Then the temp go almost to the red. Its seems like the fan kicks in too late. Its fine if your moving. Could this be the temp sensor? If so how hard is it to change and how much do they cost? It also still has dexcool in it so I plan to flush it and change the thermostat.