Most probable issue is clogged outlet from Fuel Tank.  Oh yes, it will eventually happen.  Most often seen at higher elevations or hot ambient temperatures, but summertime is just right.  This is a very common problem, after 40 years.  There is no cure, but is a cheap fix to replace gas tank.  You will need to do it sooner or later anyhow.  Of course at same time, replace the crossover tube, and every gasket and hose in the general vicinity.  Dennis was very instrumental on pointing out this problem area, and he was exactly correct.  Ken at VanAgain and GoWesty have some instructive videos about the whole situation.

    On Saturday, December 14, 2024 at 07:45:10 PM PST, Markus Benne <mbenne@m-bass.com> wrote:  
 
 Hi, for most of the summer the engine bogged once in a while, but continued on normally.  Happened about once an hour, usually after hours of driving normally.
When this happened, I did notice the tach dropped to zero before returning to normal.
Yesterday, picking up black Friday splurges for the bus south of the border, it happened more often, and twice the engine died and required me to manually restart it.  This severity of the issue is new.
Finally, on our street it died, but I was able to coast into my own driveway.   That, my friends, is the right way to break down!   After many start attempts, it finally sputtered, started, and ran fine again.    It was too cold to trouble shoot, but that certainly would have been the time.
Any suggestions on where to start?  Since bus season is now over (that was the last trip of the season) I could do some stuff, but I really won't know if it fixes anything...it's a non-deterministic issue.
1990 Vanagon w 2.1, engine is completely stock.  Only maintenance in my 6 years of ownership is oil changes and an air filter change.  Might be due some love.
I travel with quite a few spare parts, so I can swap most ignition parts like coil and cap and rotor, wires, but if this smells familiar to someone, happy to hear some thoughts.
Thanks for any tips.