Electrical gremlin- urgent help needed!!
 

Just picked up an s8 tonight & started driving it home. Got 120 miles on the road & it suddenly cut out.
It will start & run for a bit but then cuts out again, like a stall.
Any ideas??

Define 'for a bit' hours, minutes, seconds?

Originally ran for about 1.5hrs.

Stopped at the services for food and a p,
Entered m-way again, got about 2-3 miles and suddenly lost power.
Engine died and stalled. Nursed it to the services & now it won't go any more than a few mind at a time without cutting out.
Lights behind dash appear intermittent, dunno if that's got anything to do with tw problems or whether that's to do with the interior lights or not.

If it starts to misfire and gets gradually worse until its basically undriveable, probably with some warning lights, it could be a simple coil pack problem....

Vagcom will tell you a lot right now...

Has the car been through any significant water?

No water however it was jetwasher b4 I bought it. That and the passenger footwell is slightly damp. Would that cause a major issue like that?
I'm worried it may be more gearbox related as it seems to start n idle for a bit but as soon as there's any load on the engine in gear it cuts.

Doesn't sound at all gearbox related to me.....

Weak running engine is always more likely to stall under load....

If the drains under the bonnet scuttle are blocked then the jet washer water may have filled up around the ECU and other electrical areas, so that's a possible maybe. As IT says it doesn't sound like gearbox, more like fuel or electrical

As said does kinda point to water ingress after the jetwash, ahh and you should probably add clearing drains to your early to-do list once you get it home+++

Does it turn over OK? Could also be an alternator/earth issue if other lights are dimming.