In post #7 you state the vehicle hasn't been operated much in the last year other than a few trips.
I'm wondering if he fuel tank was kept full while it was sitting or allowed to be parked with very little fuel in the tank.
If this is the case, there may be condensation in the tank which is fowling the fuel filter(s). Or, if the fuel tank has a pump in it and the fuel was low the pump may be gummed up. Does the vehicle have 2 fuel pumps/2 fuel tanks ? Fords with two fuel tanks are known for the issues with the weak pumps that won't switch tanks and the ones with only one tank.....the "lift pump" in it going out.
I doubt you would have heard backfiring, which usually indicates a lean fuel air mixture.
I had that problem once with my E 350 high top and solved it by putting an external pump ahead of the fuel tank. it was much better and cheaper than the Ford pump. (which I left int he tank so that the auxiliary pump would draw thru. Paid about $15 for the pump kit and took the wires that powered the original pump in the tank and spliced extensions on to those wires. I brought them over the top of the tank to the front of the tank where there was a cross frame member and bolted the aux fuel pump to it. I went to a junk yard and got some Ford fuel fittings cut off a wreck and made my connections with them. Used a pump like this.
I got a 3/16 thick piece of rubber strap to wrap around the pump in the clamp to isolate the sound from the pump. No longer have the fuel tank issues I once had for a fraction of the cost of yet another Ford pump. I went through two Ford pumps before I did this. That was back around 2000 and haven't had that problem since. Last incident I had like you are having was due to some water in the fuel filter. Changed it and the Van now runs fine.
Hope you can fix it with a new fuel filter and some Gas Dry. Letting them sit around half full of fuel is just asking for this problem.
