The choke spring tension will not allow the choke to open if it is not adjusted properly. Out of the box it needs setup - loosen the 3 screws and turn the choke cover until the choke plate fully closes. Tighten the 3 screws. Take the throttle lever and rotate fully once, or press the pedal to the floor once, then release. The choke plate should open slightly. Start the truck - it should idle at 2000+ rpm - 1 tap should bring it down to 1600 - 1800 rpm. After that it should be stepping down on its own. Adjust the choke screws behind the choke spring to get these results if it does not step as described.