Idle air is brought into swirl prechambers outside the exact intake so that the injected quantity is vaporized as thoroughly as possible. This was most inportant on KE (or any K) systems as the injcetors were spraying all the time and the valves weren't open all the time. It helped keep fuel from puddling.
As a 92 you could have either KE or LH system depending on the car. The 140 and 124 cars only got LH and later ME. The 129 started with KE and went to LH in 92 or 93, so I'm not sure what you have.
Bosch Master, ASE Master, L1
33 years MB technician