Exactly. It'd be a leak post turbo, pre cylinder. Not seeing any leaks on the manifold or TB but going to replace both gaskets just to see.Just noodling out loud here....too rich means too much fuel so are you thinking that the pressurized air is leaking out before going into the throttle body? You have only two places that can do this at the bends, unless the TBI has gasket leaks or intake manifold gasket is leaking. Since you rebuilt the engine, I wouldn't think that'd be the case.