Hi guys,
I hope, you all had a great New Year eve and slept well after.  
Now, back to the puzzle.

I have a friend with a '87 Vanagon bus.  He says, he has changed almost everything; Temp II sensor, Oxygen sensor, computer, distributor, cap, rotor, cables, plugs, new injectors, AFM, ICU, idle control valve, cleaned all the grounds or put new connectors on, etc.

Now, he says, the car is running shabby, and when he takes off any of the cables, the engine does not seem to change running any different.  
This guy is probably the best equipped mechanic in the country with all the imaginable testers and the best Snap-on everything you can dream of.  He works on Mercedes, BMW, Porsche, Audi, VW, 
But he loves to drive his Vanagon and this is the only car that gives him the most trouble of all, he says.
He is totally baffled, confused and embarrassed.  He asked me if I would send this message to the list, in hope there is an idea he did not think of.  He is puzzled, shaking his head and can't believe it.  
But, he says, evey now and then the car coughs a little and then it runs great for awhile.  
I could not help him.
Anyone?
Many thanks for all the help I got from the Grand List so far.  
With the best regards,
Zoltan