Purchased 1973 duster a few weeks ago need help

Congrats on an amazing car!!

First, in addition to the suggestions above, take a look at your fuel supply to the motor. I'd replace the fuel filter ASAP. It's a cheap, 10 minute job that could eliminate a failure point. Next, take a whiff in the carb and the tank to see if there's still some varnished gas in there. The smell is unmistakable...I agree with those who suggest a carb rebuild regardless, but at the very least, evidence of varnished gas is a strong indicator that you could have a gummed-up fuel line prior to the filter.

Second, perhaps obvious but it might not hurt to mention regarding this feeling of something holding the car back-- you can eliminate the concerns over dragging brakes or wheel bearings by doing a basic coast-down test with the car in neutral. Obviously, it should roll right along easily under its own momentum.

Double-check that parking brake to make sure it's fully releasing. ;)