Last winter my 200GT started running cool. Prior to this I had the common RPM fluctuation/engine die. It happened only sometimes, and seemed worse in the damp or rainy weather. Anyway, after replacing the wore out thermostat with a AutoZone OE equivalent it seemed to be much improved. Since last winter, I've only had one or two times that it died. Don't know if this is a FIX, but the replacement did help.