That sounds like a float/needle valve and seat problem in the carburetor since you said coming to a stop and while turning. Does it have a clear fuel filter on it where you can see the fuel level in the filter? Could also be a charging issue or that could be a separate issue. If you have a digital voltmeter or can get one, put it on the positive and negative terminals of the battery when its running and let me know what kind of reading you get. Do you know if it's a 6v or 12v system?
Did it keep rolling or just move a few inches? There's what is called a parking pawl that locks the transmission in park, but it has a little play. You can actually push the car back and forth slightly. This might be a dumb question, but was it all the way park?
There are 6 cells in a battery that hold 2.1v each, when one of those goes bad it can cause all kinds of funky issues. The newer conductance battery testers are awesome at finding this. And you can't beat that pretty much all auto parts store offer free charging and starting system tests in an attempt to sell more parts. And you're right about the weather. Every year when the cold first hits, cars with bad batteries start pouring in like clockwork.
it definitely rolled a couple of feet before I got to the emergency brake. and it was definitely in park lol. I distinctly remember because I felt what you were talking about above, the parking pawl. Every time you park it you can feel it jerk forward a couple of inches before stopping, its very distinctive in that car, and for some reason I really remember noticing it before I got out of the car.
for the volkswagen id start at checking grounds i had a friend with a truck that would stall on bumps and stops and not charge right..then one night we noticed spark between the metal bumper and the fender...turned out the body was not grounded right to the frame..we fixed the wires from neg to engine and neg to body and added a third straight to the frame and everything worked right again
It could have a shifter or linkage problem where it said it was in park, but it was actually in between reverse and park. Did you have to mess with the shifter to get it started again? The parking pawl could be screwed up too, I've seen that happen from putting it in park before the cars stopped all the way. Either way I'd tell them so they don't get back to their car one day and it's at the bottom of a hill smashed into a light pole or something. Lol.
I just had something similar on a dunebuggy happen. The output from the voltage regulator was chafed and shorting to ground at times on the trans case, then it would die. Other times it would charge. Talk about a nightmare finding that on a dunebuggy, I ended up rewiring the entire car. Old VWs are cool but their wiring drives me nuts.
