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.