1976 f250 390

My truck won't idle when the thermometer drops below 40 degrees. It loads up, I wait a few minutes the plugs dry and its fine. Heres what I've tried so far.
Replaced plugs, wires, cap, rotor,coil, all filters ignition control module, distributer,rebuilt the carb,and I run hightest in it. I really think its the carb.
This is my first post on this forum I hope you guys can help.

When you rebuilt carb did you replace choke spring?If electric choke check for current.If equipped with choke pull-off ,chesk operation.