yeah, get some of that tin foil like induction pipe from any motor factor and run it from somewhere on top of the exhaust manifold to the air intake so it sucks in warm air from over the manifold.

just try it temporarily first by wedging/cable tying it roughly in place and go for a high speed run when its very cold out. if it runs fine then you know its the problem and can make it more permanent (until summer then take it off again)