E450 - Widow's engine won't start (2002 Conquest)

If it is a Ford gasser, just find a good ford truck mechanic and have them come an look at it. Gould be any one of a lot of things, most probably small. Bad gas is a good place to start, fuel flow or not is probably the next place. If it fired with the ether, that probably clears the ignition system. Most likely is the fuel system, including filter and pumps.