Wesley;
    I fought this battle on our 85 . The last thing I did was
rebuild/lubricate the moving parts that make up the timing advance in the
distributor.
    I believe it was getting stuck fully advanced, so holding the throttle
wide open lowered the vacuum, hence retarding the timing closer to normal.
    A part of regular maintenance calls for a drop of oil on the felt button
under the rotor(digijet only). How many people do that!

Ken Lewis
86 Transporter Crew Cab
60 356 T-5 Porsche
http://neksiwel.20m.com/
Vanagon tech, pixs, O2 monitor gadget