Won't start one day and fires up first crank next day

I've been known to "rig" a temporary pilot lamp or meter connection so I can monitor a "suspect." See if the coil + is getting voltage here is how

When you go to start it, turn the key to "run" FIRST. Look at coil+. It should be say, 6-8 maybe 10V and NOT as high as battery. This shows it's getting power, drawn "down" through the ballast AND THAT the ECU is grounded AND drawing current.

Next crank it using the key and look again at coil+ Now it should be "same as battery" and that is, if the battery is pulling down, say, 11.5--11V during crank, then coil+ should be "same."

Check spark. "Rig" a test gap using SOLID core wire out of the coil tower to a wide gap plug or spark tester gap. I have a Lisle, not terribly expensive, and works.