new to list(hi all!) with a problem i hope hasn't been covered a hundred
times before (altho if it's a standard thing maybe there's a solution...)

85 Digijet Westy, ran fine for 4 months after purchase, started running
rough so took it in for tuneup. Subsequently, it would start and run fine
but stall out after 10 mins of operating. (Mech couldn't offer any
conclusions about what his contributions to problem could have been). At
first it would recover after sitting for 10-15 mins but later woudn't
restart at all. Diagnosis by another shop revealed it was no spark when it
stopped running(rather than fuel, which I would have suspected). Hall
generator was replaced on shop's recommendation but it didn't solve it. 
It's back in shop again but I don't think they'll figure it out: these
intermittent problems are so difficult to control enough to get a proper
read on them. Has this sort of thing ever been discussed as endemic to
Vanagons of the 85 vintage? If so, maybe a VW dealer would have a bulletin
on it. Any help greatly appreciated, I got this car to replace my 67 split
and I absolutely love it, but it hasn't run reliably for most of a year and
I want to go CAMPING!!!!
Thanks
David Griffin
75313.377@compuserve.com
85 Westy
78 GTI mutant