318 Accelerator Randomly Hangs

On my 1972 Dodge Dart 318 engine. the 2 bbl carburetor was rebuilt this summer. Randomly the peddle will not return usually at the 30-35 mph mark. A quick kick of the accelerator with releases the hang and everything is normal.
I have replaced the return and kick down springs. Could it be something internal caused during the carb rebuild? Ideas where to look?

Thanks