1987 Nissan Truck throttle body

I just changed my motor in my truck. its a nissan d-21 pickup with a z 24 4cylinder. i put a new crate motor in it. i believe that something is wrong with the throttle body on it. you start the truck and on the left side of the throttle body its just shooting gas in it and the gas is coming back out to. if you push the gas pedal it just cuts off. i dont really know whats causing it to do that...