Do you own a noid light set? If not, would you be willing to spend $20 to buy a set? They're essentially fast-responding test lights with pins you can plug into various connectors for. I have this set here;
You can plug a noid light into where the coil would normally be. When you crank, it will flash, indicating it's getting the proper signals to the coil. You can also use them in place of injectors (to verify injectors are getting signal) and various valves.
What this will tell us is if the problem is in the coil/ignition/dizzy/wires, or if from the ECU/Power supply itself.
'91 Frankenheep YJ. 4.0, 4" BDS, Richmond 8.8, Titan 12k, 35" KM2's, rust.
'88 YJ, 4.2/4.0 head, +4½" & shackles, BFG 33's (sold)