today i started the task of removing all my smog equipment and doing the throttle body mod. when i was removing my lower intake manifold a small round piece of metal fell out right below the 2 primary intake ports on the engine. It is about the size of a silver dollar, i think it might be a soft plug. if someone could tell me what it is for and why it would fall out on me because i can see right into the engine with it removed and what i would need to replace/fix this problem.