Engine bogs when accelerating

[Elpresidente]

I've got an '82 Chev Scottsdale, 305 4bbl/700R4.
Since its freezing here (-40 this morning), my engine's had a problem of bogging down when I accelerate. It gets worse as the temperature outside drops, but after the engine & tranny warm up from driving a mile or so it runs fine.
In park or neutral it idles and responds well to the throttle, its when I put it into gear that the problem starts. I have to feather the gas to keep it running.

Even if I let the truck idle and warm up to operating temperature, it still bogs down a bit. Its definitely due to the cold weather, because it never did this before winter came.
The engine's clean with all new filters and plugs, so I can rule those out.   
Im thinking maybe the transmission (because the problem starts when put into gear), or the choke sticking. But how can I tell?

Any help appreciated.
Thanks.

[Grim 82]

It bogs down when you put it in gear only because of the extra load on the engine. You could try stepping up the idle a little bit, or richen your fuel mixture. Cold motors like gas.
If it doesn't fix itself after having fully warmed up and been driven, I would suspect the accelerator pump.

[Cody1018]

Could it maybe be due to the butterfly valve in the carb sticking when accelerating?

[Elpresidente]

doubtful, but regardless ill clean it out as best as I can and adjust the idle a bit and see if that helps at all.
Thanks