Hello I am new to this forum and the Audi world as well. I have a 97 A4 v6 5-speed with 110k and a little bit of an idle problem. While in neutral the rpms dont stay flat, the needle moves up and down about 50-75rpms.
It dosen't seem too bad but I wanted to know if this is normal or do I have sumthing very wrong going on? Any information at all will be a big help. Thank you.

 

If you haven't done the timing belt job, it could be a loose tensioner.

 

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The most common idle problem is dirty throttle valve. you clean it with a special solvent.