Re: 1985 E-350 giving us some trouble
Did you have any good luck yet on getting going. If there was reworking done to the fuel system I'd be looking for kinked fuel lines along with what was stated already.
If you have a diesel which I'm sure you do with a return fuel line you could be looking at an injector pump that may be leaking. That is often seen with fuel going into the oil. Other thought that comes to me is how is the weather outside? If it is cold enough and you still have #2 diesel fuel in the tank that may be a problem. A bottle of "diesel 911" would help at that point. It is a red colored bottle.
Please do let us know what comes out of this.