IF THE TEMPS ARE IN THE 30S - 40S YOU MAY BE GETTING CARB ICING, WHICH HAPPENS WHEN AIR (USUALLY ABOVE THE FREEZING point) LADEN WITH MOISTURE, passes through the carb through the throttling process which lowers both the pressure and temperature below the freezing point of water in the air. It freezes up on the throttle plates, idle circuits, boosters, etc. The reason this happens at temps just above freezing is that once the air temp is below 32F it has very little capacity to hold water vapor.
In the case of carb icing what you need most is a carb air heater; ducting the inlet air across the hot exhaust manifold so that the air becomes pre-heated to the point that carb icing cannot take place. You can use factory parts to do this or make a facsimile if you are handy.
Good luck.
6re6
