I have an '82 air cooled vanagon.  It jerks, shakes, hesitates, bucks when it reaches around a certain rev, just about when I would change gear or reach the cruising speed.  Last year it did not do it, but other than that it did it for the last ten years.  I tried numerous things and I could not stop it.  Sometimes its worse than others.  
Is it a thing I can ask the list to ponder over and be successful solving?
Zoltan  

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