Mystery A/C prob & idle surges

[ArmchairExpert]

Sorry to take so long to respond.
There are six vacuum elements in the late model W124:
Defroster Flap 1
Shutoff Flap 1
Cold Air Flap 1
Main Air Flap Left 1
Main Air Flap Right 1
Legroom Flap 1 (Early models have 2; 1 left, 1 right. Our later 1990s models have only 1. Some DIYs may show the earlier version. Everything else is in the same locations on early and late, though the actual elements' part numbers correspond to the model year.)

Here's a link to Redlinemotive's page that shows them for an 1994 E320 Wagon. There are door lock elements and the gas flap element listed below that are not involved.
Replacement Parts Catalog
Everyone sells Behr, never seen any other brand.

[ArmchairExpert]

Mercedes has a free online parts catalog.
EPC-net Online
You need to register and have your VIN ready as the site will give you exploded views of systems based on your car's build sheet. If perhaps the exploded view shows parts that are not in your car, when you click on that part, instead of a part number it will tell you N/A for your build. Really nice. This helps weed out parts you wont' need before starting a job.
Good luck,
Dennis

P.S. After loading the EPC, depending upon your browser's security settings, you may get a warning that the site is trying to run a potentially dangerous
JAVA script. It's safe, let it run.
D