My Motorcraft 4300 four barrel worked flawlessly all summer (remanufactured)but as soon as winter weather set in, it won't allow my 71 T-bird to move until the car is fully warmed up. Putting the car into gear kills the engine. Until the car is warmed up for about ten minutes, giving it gas will cause it to stumble and then bog for a block or two until it picks up speed. All settings are correct. It's pulling 20 inches of vacuum.

Optional Information:
Pre-1980 Ford 71 T-Bird 429

Already Tried:
Checked all carb settings and mounting studs.