1966 Dart troubleshooting

The choke being open when the car is warmed up is normal. It should however reset to closed on a cold engine after throttle is depressed once.

Sounds like you may have a blockage in the idle circuit. While some symptoms suggest accelerator pump, it is often possible to accelerate slowly and get past that, and idle would be normal.

One simple fix is to try to clear the idle circuit at idle mixture screw. From the present setting lightly screw it in while counting exact turns. Then screw it all the way out, clean it with a shop towel and carb cleaner. Then use the red tube on carb cleaner to squirt cleaner in the carb where the mixture screw was removed. Carefully replace screw, lightly seat it and back it off the number of turns you counted.

If that does not fix the problem, it is time to put a kit in the carb. If the carb is a holley 1920, the metering block has internal passages that may be difficult to clean.