It sounds like you are having an intermittant problem.  My gut feeling on
this one is that your ECU is the problem (could be a lot of other things but
this is my first impulse).  If you can find someone with a known good ECU
that you can swap into your van to see if this fixes your problem, that would
be a good thing to try.
Of course I would first, look over the motor for any broken wires, etc
(something more obvious) first.
Hope this helps,

Ken Wilford
http://www.vanagain.com
John 3:16
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