Runs great in summer ...stalls all winter.Please Help!!!

My 1988 Mazda B2200 pick-up has been running like a dream but as soon as the weather started getting cold I have had many problems with stalling and bogging. The truck will idle fine but as soon as you step on the gas it boggs and eventually stalls out. I also notice some high metal clicking noises comeing from the area of the air cleaner assembly or carb. There is no pattern to the clicking.My first guess on these problems was the choke but it seems to be working. Next is the vacuume system, but I have no knowledge of this. Can any one please help me figure this out. An email would be greatly appreciated. Thanks in advance.

Steve.
ianni316@aol.com