This is a head scratcher now.....
ok a question. did you keep the original ICM? if you did, does putting it back on give you the rough running?
next possible thing that I can think of is tht it might be fuel delivery related.....as in the actual pump in the tank, the relay module itself, fuel filter or bad pressure regulator. Unlike the 5.0 cars, the relay is part of a relay module found on the passenger side shock tower - its the big honking electronic box with alot of wires going to it. From what i understand that box also controls the fan and it isn't easy to open up to just replace the relay.
I'd start with the easy stuff first - drop the fuel filter and when you have it off, have a helper turn the iginition on for a second or two to see if you get some fuel pumping out of the line - if you don't then the next step is to determine if it's the pump or the pump relay.
Just throwing a wild guess out there.