if you are talking about a 3/4 in fitting that is directly behind the throttle body and has a big and a small hose coming out of it, you are referring to item 10+9 in the diagram. if it is leaking from the mating surface between the manifold and fitting, as you can see from the diagram, there is an o-ring that goes in between there, and that might be the cause. ill wait and see if this is what you are referring to.