No offence but if you know how fuel injecton and carburators work then how do you not know what a throttle body is? Any way

Are you refering to throttle body injection, or just what a throttle body is? Throttle body injection is mostly used on american made trucks. It works kind of like a carburator because that is where the fuel is actually introduced into the engine, but unlike a carburator the fuel supply is computer controlled through a set of injectors. The actual throttle body is a butterfly unit on the intake manifold that regulates how much air the engine is recieving. As the butterfly opens it allows more air and fuel into the engine causing rpms to rise and more power to be made.