Okay, so I've just changed the timing chain, and I got a question..
Before changing the chain the car "jumped" a little sometimes on idle In netural and the sound in the exhaust disappears with it, after changing the chain the problem stays the same.. could this be the spark plugs? I got Bosch plugs at the moment, would it be better with the factory ones? Any thoughts? I have asked a little about this before, some one saying it might be a injector leaking, any of you guys have any more possibilities to add?
Give the airflow sensor a clean, don't touch it , just buy some electrical component spray, cheap and could be your issue, although it could be knackered so may need testing. I believe it is okay to run the engine with the sensor unplugged, at least it was for me, throws up an EML obviously. Double check for your scirocco though. If the bad idle doesn't persist with it unplugged then it'll be the sensor. (If it is the sensor, only replace with an OEM part, stay clear of knock off ones as they'll cause more issues than they'll solve I've heard)
Is it the same at all engine temps?
Injector is a possibility but you would likely find your issue to be more than just a little jump. Best to rule out the cheaper possible solutions as testing injectors are stupidly expensive if I remember correctly.
I had this issue on a cold start with my previous car an E46 diesel, so I've read just about everything there is on causes of a bad idle , being diesel mine had 3 issues , 2 dead glow plugs, partially dead glow plug control unit and the rubber had given out on the crank pulley, all contributed to the bad idle. Obviously glow plugs are irrelevant but check your pulleys for wobble.
Not clued up on the timing chain side of things but it's likely your issue is related to that still.
