Your problem sounds electrical in nature to me.
Could be the ignition switch (these are notorious for going bad).  Do you
have a large keychain/ wad of keys?  If yes, then bingo!

Also it could be something in your ECU heating up, causing the van to die,
cooling down and doing the same thing over and over.

Check your grounds on the engine, cap, rotor, plugs, etc.

Hope this helps.
Ken Wilford
Van-Again
John 3:16