At idle or low speed coasting the car will essentially lose all power for a second. The dash/headlights/instrument cluster will all turn off and back on. The clock and trip odometer reset. The various warning lights will come on as if the key was just put in the run position. Then I can turn the key off and the car will start right back up.
Doesn’t happen at higher rpms. Car be in neutral and idling or if I’m taking off slowly or coasting along slowly it will happen. Battery voltage with accessories on is 13.9v. Battery terminals are clean and tight. I am going to dig into all the grounds but since the alternator seems to be working fine and the car will stall sitting still I’m not sure which ground would be corroded or broken since it wouldn’t be breaking contact while sitting in idle.
Any help is appreciated especially from vw/Audi techs.
Faulty ignition switch is the first thing that comes to mind. But that wouldn’t explain the clock and trip odometer resetting. Make sure the connections at all ends of the battery cables are clan and tight. Just looking at the connections is not a definitive way to tell if they are clean. You have to take them apart.
Since the clock is resetting that would mean the trouble is before the ignition switch. There could be a problem with the main ground lead also but I suspect the problem is on the hot side of the power. Check the main panel under hood along with the power wire between the battery and that panel. Make sure the main fuse is making good connection also.
Ignition switch or battery problems seems most likely. If you feel lucky you could try replacing both, see if it helps. A good auto-electric shop working the problem is what you need though.