Audi A8 2.8 running issue

[Audi Doody]

Hi all,

Have had my A8 since May, and in that time have covered 2340 trouble free miles.
That ended today however: the car started well enough and I drove it a couple of miles. I went to pull away from some traffic lights, and the engine stalled. So I put it in neutral, restarted it and it crept, but was unresponsive to throttle inputs. I pulled up to the side of the road and turned the engine off and restarted it. The EML, ABS and EPC lights were on. Also idel was erratic, jumping between 800 and 1200 rpm. The throttle would let the engine gently rev to 2k, but not past - this was only in neutral, in gear it was idle only.
Anyway, I managed to limp home at 10 mph using creep, I had to stop a few times, and when putting in D, it would do so with a bang.
Pulled in my drive, turned it off, turned it on again, and all the dash lights were out, and idled and revved fine! Took for a very quick test drive and it was faultless - moved in to D smoothly.

I know it needs diagnosing; but is anyone familiar with this? Very annoyed as I was planning on going to Europe this week; am happy that it decided to happen now though..