My 1997 chevy van will cut off while driveing and then won't start back up right away and sometimes not at all. I sprayed starter fuid in air box to get it on a trailer and the van stayed running for about 5 minutes and then cut back off. sometimes cranks back up. not sure where to start

There could be many things to cause this problem.
Ideally when it quits is the best time to begin the diagnosis. First thing is to check to see if there is spark at the spark plugs when cranking and listen to hear the fuel pump run when you first cycle the ignition on.
But going on experience and what you have told me so far I would begin with ignition problems.
Because you mentioned it quit while driving and restarted after a cool off period it makes me think that an ignition part is failing when hot.
Engine heat and electrical current flow can heat electrical circuits, expand them, and go open circuit.
An ignition module, the pickup in the distributor or the ignition coil would be on my first checklist.
Give me a note back if you need more leads.