Cold outside is a problem. Are you covering the head with something? You really need to cover the head so the engine can run rich and warm. Most 3.3 engines need to be set at 5 or more turns out (hsn) to perform well in the cold.
with my 2.5 I'm running 5 and and half turns, and i keep my head wrapped in foil. of course i live in Mn so if i want to play i gotta re-tune just about everyday based on the temps!