Seems to be a common complaint about Vanagons, that intermittent poor
running. Mine (86 Westy BusPlus) had a repair bill from previous owner
alluding to same problem, without diagnosis!

Sure enough, we too had intermittent problems on long hot summer trips,
where van felt like it was running on three cylinders (turns out it was).

Two solutions: 1) we took van to dealer, and they found one of the spark
plug connectors failed when hot. Seems that the resistor connectors have a
limited life when used in the hot environment of an air/water cooled
engine. They replaced the bad connector et voila! Pas de problem. Since
then, I have replaced the entire set (Bosch wire sets ~ $60 at local parts
house), and keep newer used ones as road spares. Consider it a regular
maintenance item if you travel in hot weather.

2) Traveling through Utah one summer, similar engine missing, poor running.
I thought it was those pesky connectors again, but it turned out that it
was simple: the rotor and cap were pitted, although low miles on them. I
didn't have spares, so I cleaned them with emery cloth, and traveled on.
Traveled through Colorado, but it wasn't until Jackson Hole, WY that I
could find Vanagon cap/rotor in stock!!!!

Note: American cap/rotors are worthless. Get the Bosch. Cheapos don't last
at all. Ones I purchased in WY lasted til home, but were shot by then.
Also, buy a spare set and keep it in car. Well worth it.

#2 goes to show that sometimes Vanagon problems are as simple as old-time
VW bus problems. Don't always suspect "brain" as my friends do.

Mark Mellander
86 Westy Bus Plus
Past owner of 61, 63, 66, 70 Bugs, 69 Van, 68 Ghia