If you change anything to do with the throttle control, turn the ignition on for 6 seconds before starting. In theory this will check if a basic setting is required (after a battery change or replacement of parts) and do it. There's no obvious sign it's been done, so the manual process with VCDS does give some confirmation that all values are in range.

Mine was an 02 - yes it threw an post cat emmision code but doesnt hurt anything.

Damn - the problem is back again, less than a year after fitting a new throttle position sensor.

Exactly the same symptoms and, yet again, towards the end of a 30 mile drive in heavy rain.

But then after standing at work, no problems on the way home or the next day.

I'm more convinced it's a leak and my local Audi indy says there is a leak, but on the n/s, but that all the drains are clear - Botang's hole perhaps?

So, if it is Botang's hole leaking, could water find the throttle position sensor, or associated electrics?

It's going back in a week or so for a more thorough investigation (so pray for a dry spell as I need the car for a couple of key trips!), so I'll update this when I know more.