2002 Dodge Caravan

2002 Dodge Caravan

my father in-laws van will stop running during drive after about 15-20 minutes of 55mph. It will shak alittle just before it shuts down and we have to wait 25-30 minutes before it will start again now when it first shuts down and we check for spark it doesnt have spark but right before it does start we get spark. We thought mabe the fuel pump but it does kick on when started. We have replaced the coil pack, and fuel filter, and the cam sensor.
we are not sure what else could be causing this problem.