Ran out of fuel and car hasn't quite recovered.

[AMGCoelho]

Hi guys,
I've got a 2004 RS6 Avant. Turns out my petrol gauge isn't very accurate so I ran out of fuel. The AA fixed that but it's never been the same since.
The idling isn't right - it chugs between 800revs & 2000 sometimes. Makes odd sounds, Splutters & sometimes completely cuts out. It's fine on the motorway though.
The AA guy said that 4 of the 6 cylinders weren't functioning at first and then thought maybe it was the gauge. He refueled and it started up so decided that the gauge was probably it and left. Could he have left something open? Any other suggestions? Thanks very much.
PS: not too much jargon please.

[b7rs4saloon]

Your in the wrong section

Your RS6 has 8 cylinders not 6

I would change fuel filter first

[AMGCoelho]

Thank you. I meant 4 out of 8 sorry. Ok I'll get that looked at. Which section should I be in? Thanks for replying

[Eddie555]

Thank you. I meant 4 out of 8 sorry. Ok I'll get that looked at. Which section should I be in? Thanks for replying

C5 RS6 section.

[AMGCoelho]

Thank you