the thing between the throttle body and intake manifold. just wondering

 

its essentially a gasket, but there are many other names for it too

but its also a spacer as it has ports for vacuum

http://www.atkinsrotary.com/store/In...-Body-Spacers/

 

no not the gasket. the part stamped with 13b and mazda

 

this and also what is this

 

the upper plenum chamber, since the non turbo cars actually have 3 intake manifolds pieces.

the second item is your BAC, bypass air control valve, it controls base idle to a small degree.

 

please excuse my ignorance. thanks

 

The upper plenum is actually called the "dynamic chamber". It stores pressure waves and at higher rpm's allows the stored pressure into the engine for a supercharging effect via the 5th and 6th ports. This is why its critical to have the ports clean and operational and the of course the port actuators working properly. If the system is not working properly, the engine will be sluggish in the upper RPM range and will feel like it underpowered.