Just bought a 2000 A8
and on the front of the motor, front side of the intake there are two vaccum cyclinders with control arms going to spring levers, to me it looks like they control maybe butter flys on the inside of the intake? i'm guessing, for cold starts? one lever is missing and the other is frozen wont move. ill have to take a pic.
I'm new to the Audi world. not new to wrenching. I have a 1994 ford lightning full drag truck, 9.80 1/4 mile times

 

They are vacuum operated crossover valves
not butterflys but 2 long cylindrical tubes with ports.
as you get on it the crossover tubes turn and funnel air through the intake faster

Don't think they're that easy to move in resting but you can test them with a vac pump. or note the position and start the car.

Is it running right without that arm. I would think it would run like shiz.

You'll need to replace the missing arm
junkyard or Audi is your best bet

 

thanks> leave it up to a newbe> i did some reserach on it and its common.
and it runs mint with both broken. i can only imagine how it will run with them

 

This is the only place I've ever found them without buying the whole thing ($400) per side.

gruvenparts.com - Billet / Composite 4.2L V8 Intake Manifold Linkage Arms

Recent discussion of them on AW in D2 and D3 forms