I know where the injectors are, and what they do.
I guess what I'm trying to say is that air is the only thing that flows through the TB, but the bottom half of the TB, below the butterfly, will often be coated with carbon/oily black build up.
the bottom of the TB is exposed to the sludge that is expelled into the intake manifold from the rear CCV line on the valve cover.
fuel system cleaner poured into the gas tank will only clean carbon from the injectors and cylinders.
to clean the sludge from the intake manifold and below the throttle body, I used the stuff that is connected to a vacuum line and dripped directly into the intake manifold to clean the runners, along with a spray TB cleaner misted over the TB while opening the valve.
(although this all might just be snake oil, and I don't know what I'm talking about.)
:wave:
B