2004 Kia Sedona 3.5l not getting fuel for a while

My in-laws have a '04 sedona.  After a 15 minute trip to the store then ideling for 5-10 mins began to run very rough then stalled.  
My father in-law was able to restart and drive a few feet before it died again.  I came to check it out and it still wouldn't start an
hour later.  The engine had spark but no fuel, it started and ran for a few seconds when we sprayed starting fluid in the throttle
body.  I returned to do some diagnostic today about 20 hours later and it started and ran rough but not as bad as it did for him.  
I drove it about 15 miles mostly trouble free, had a rough idle and seemed low on power.  Since I brought it home I have been
trying to recreate the problem by allowing the van to idle for 10-30 mins at a time shutting off and restarting.  I can't get it to stall
now.  If anything my running it has improved the idle.  I'm stuck I can't fix something if it doesn't at least act broken enough for
me to find the problem.  Due to my father in law's poor health I don't want to just send him out driving it and have it break down
again.  Has anyone had a similar problem with their Kia and know what fixed it?   I would appreciate any help or direction.  Thanks