I have problems with mine in the winter. when it's cold it will not warm up all the way. I have put 3 different thermostats in and still no luck. if it is 50 degrees or warmer it is fine and much colder it will not go to opp. temp. If I drive it around and it is warmed up and you are just sitting there idling the temp will come up, but when you start driving it will drop 2 spots. any ideas?