Well I bit the bullet and ordered a used computer. It should be here on Friday. It's out of the same model year, engine, trans and a running accident truck so hopefully it's my problem. I think it's down to this; since I can't link up to the computer the problem is either the computer itself, or the wiring for it. If the engine doesn't start with the new computer then I have some wire tracing to do. Luckily I do have the factory service manuals for it, so at leas ti have that going for me.