Intermittent starting problems

I agree, doesn't matter vehicles, aircraft, U.S. Navy RADAR, electronics, amateur radio, or TV / audio, intermittent problems are the worst.

I've gone as far as rig up nasty lookin temporary pilot lamps at various places to see what is getting power and what "aint."

Don't discount ANYTHING. Could be a corroded terminal in a connector, ANY connector in that circuit, or a bad ECU itself. MAKE CERTAIN THE ECU is grounded. CERTAIN. You can tell with a meter "if you catch" the problem by turning on the key and measuring coil + to ground. A grounded conducting ECU will pull coil+ voltage down to about 6-8 v with key in "run" and coil NEG with be maybe 1-2 V "Full battery" at coil + and - means coil not conducting through the box.