'74 Duster - stalls easily

Hello! I have a '74 Duster with a 318, 2 barrel carb. A very solid car, no rust, and less than 100,000 miles on it. It will start easily, and idle fine after it warms up. However, if I take it for a drive (just around the block so far) it will stall when I let off the gas. I made 100% sure the engine was at it's normal operating temp while doing this. I'm using fresh gas. (I don't know too much about cars, but I suspect this may be a carburetor issue.) I plan on giving it a tune up to see if that helps, but in the meantime if someone has some pro tips, I'd appreciate it.

Thanks!
- Dave