[mickmate]

I had a Superformance here where the pedal had stripped it's attachment to the shaft. The pedal couldn't be removed with the motor in place so I welded it to the shaft for now. It sounds like it is binding where the nut holds the assembly together. Check that first. Make sure you're throttle isn't running out of travel and bottoming out as that messes with the linkage and as pointed out have at least two return springs, one on the carb linkage and one on the pedal. Check out SCOF as it's a wealth of knowledge on these cars.