Carb Problem

[stepsider]

!972 Stepside 350 ci & 350 tranny. Had the Carb rebuilt because the choke was not working, was zip tied open, Don't know why. Carb check out as a 72 Q jet 4 Barrel. Replaced the choke spring from Napa. $ 49.00 dollars !! Now the problem,

Car starts & runs but the kick down doesn't work. Run for ever at a fast idle until I move it by hand off the fast idle cam. I'm guessing that why the had it zip tied open. I should be able to set the fast idle when cold with the gas pedal & should be able to kick down the idle wi a tap of the pedal. They told me my model carb won't accept a aftermarket electric conversion ?? Need Some advice or answers.