69 Fastback 351W .030 over, mild cam, C4
Bought the car a few months ago. All work was done by previous owner. 351W summit 600 carb. Motor rebuilt less than 2,000 miles ago, carb has less then that cuz he originally had Holley on it that he couldn’t get to run right. PO told when starting cold to push throttle all way down one time to set choke. Turn key. Worked perfect till weather turned cold. Last 2 times when it lights off it’s like the throttle is stuck wide open. Revs to the moon for a split second then comes back down. What should I look for that could be causing this?