Engine rough Idle got fixed!! Here is what they did.
 

Ok so I have been having some issues with my car running rough like when at a light it vibrates alot and stuff...Well after the dealer I was going to telling me everything was ok and i was pretty much crazy (IRA AUDI BOSTON..PUKE) The new audi dealer I go to found out the problem....Here is what they found

Vacume lines to combi valve T and to combi valve defective and falling apart...Replaced vacuum lines. RR intake, intake hose, metle intake, RR Rear braket off motor and replaced assorted vacuum lines, Ran GFF and cleared codes and ran basix settings and tested to manuf spec.

Not really sure what all these parts do or what vacuum does for the car but I can tell you the car runs GREAT and smooth now! Anyone wanna go into what these parts do? Thanks for the info...and I hope maybe someone with the same problem finds this helpfull! 2004 A6 2.7T S-Line AWD Auto

I agree anyone that is a audi god that can let me know what this is so i can tell my roommate and let him fix it?

Instead of using electric solenoids some parts utilize vacuum from the engine to operate. Older American cars did this but they have gone away from it as they persue cars that go 100K on oil changes and gas (smart). The little rubber hoses just rot over time and they are quite easy to replace if you take your time and replace one at a time. They just pull off and push on. If they crack or brake the parts that use the vacuum won't be able to operate and cause a rough idle, stalling, hesitation etc.

You can purchase the OEM style braided vacuum tube from www.ecstuning.com the 5 meter roll almost did both of my cars I was short 12 inches. The hard plastic tubing I got from the autoparts store. As soon as you touch that stuff it breaks.

Who did you use to replace IRA?

Well I moved from NH to Florida so I am use Audi Melborne now.

Can a cracked boost sensor fitting (P/N 078 907 597) also cause rought idle/decreased performance? The boost sensor is in a ridiculous spot mounted on a braket adjacent to the air filter housing. It slides off the braket to make moving the intake cover a bit easier, but the fittings are under quite a bit of stress, and mine has cracked, and is very loose. The hose barely stays in place, and doesn't have a good seal anymore.

Thanks,

Aaron

Thanks epr7339 for the post the same thing happened to me, so i took a chance at spending the four bucks to try it out. It worked great and now i dont have any idling problem. The vacuum is used by the throttle to slowly close when you remove your foot off the gas.