Thank you to all the members who responded to my message.

This problem had bedeviled me for over a year.

I finally took it to a mechanic who had the right idea and patience to
solve the problem. He refused to drop parts in on a guess. Instead, he ran
the van at his shop every day waiting for the time the problem would
appear. It took over two weeks but one day the van conked out and wouldn't
restart. He zeroed in on the problem. It was the idle control unit. He
removed it. I drove it for a week and so far no more problems.
The mechanics name is Tom and he works at Metric Auto in St. Paul, Mn.

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ORIGNAL MESSAGE
For over a year now I have had a mechanical problem with my 85 vanagon. I
am on my third mechanic and so far no solution. As much as I love my
vanagon (when it works), I am about ready to give up. You my list mates are
my last hope.

The problem is intermittent. It could go a week just fine and then happen.

The problem - I am driving suddenly I notice the power slumps, I push the
gas nothing, the engine just not quit right away it goes into limbo for 2-4
seconds then the dash lights come on. I drift over to the side. Put the van
in park, turn the key and is starts up just fine. I usually can drive to my
destination no problem. It might be fine for three or four days and happen
again.
Once in a while the van just won't start. It cranks fine but does not kick
over. I can leave it sit for 10 minutes or so try again and it starts, runs
fine for a day or so then any of the above can happen.

The following has been done:

1) New ignition switch
2) Rebuilt air flow meter
3) New Oxygen sensor
4) New cap and rotor
5) New fuel filter (check fuel no excess contamination)