My engine is a carbed e16. When it gets seriously cold outside (like around 30 degrees F or lower) the car won't stay warm. Basically what happens is I can start it up and let it idle until the temp guage shows the engine has warmed up but when I start driving all the cold air hitting the car appears to drastically cool the engine down and my temp guage practically goes all the way back to cold. Neddless to say when this happens my heater craps out on me. It's especially bad on the highway. In stop and go city traffic the cars cools way down but once I hit the highway it cools down extremely fast and stays there. What do I need to check out? It didn't use to do this before. The car always stayed warm in cold weather and the heater used to be savage enough to boil your eyeballs out of your head.