I know exactly what you have. This part is not original to to the car but was added in order for the car to meet Federal emission standards. My 1985 280SE does not have this thank goodness. The part is known as a Frequency Valve and is used to adjust the air/fuel ratio. The other component to the system is the oxygen sensor. If that car were mine, I would remove the junk and thrash it as it DOES NOT need it unless you live in a state with emission laws. Your car is probably equipped with a catalytic converter as well. Something else it did not have from the factory.

Good Luck,

Aaron