Van gradually shuts on/off at freeway speeds til it barely runs.Could not
restart so was brought to shop. Charged $640 for plugs, oil,cat conv.,oxy
sensor,3 hrs. labor,and adjustments.They told me at first the ECM was dumping
fuel, (that's why they replaced my new oil & plugs)then did the other
work.They said it ran fine but it did the same thing after driving it for
about an hour on the freeway.I took it back to the shop and they suggested
replacing the wiring harness for the air flow meter ($180 plus labor-$83/hr).
I said maybe later as my cash is low.Found solution of soldering 22
microfarrad capacitor ($3) to terminals inside air flow meter.(see
www.geocities.com/harald_nancy/intermitt._syndrome.htm).That didn't fix
it.Friend suggested gas cap not venting fuel tank and creating vacuum.Will
try that next.I also notice that when the problem happens the engine temp is
at the cooler end of white area  and the fuel guage shows empty instead of
half full.Any help appreciated.Thanx.