I have to admit I am a bit unclear from you description, but I have one thought.
I had a 92 5.0L as well. I learned that only on that year
the positive battery cable was very special and complicated. there were multiple circuits fed directly from the positive cable. this may be the root of the problem.
Now I am not sure if it was a great idea to be touching cables together like that as you may very easily short out the ECM, but lets hope you haven't done that.
Really, I think you need to verify power and ground to your crucial components with a proper voltmeter. as well as double check the condition of the battery.
No lights or anything would imply a simple systematic failure, tricky problems with the electrical system tend to be more subtle.