01Z28M6

Read #18 again. This was happening before and after the Blaster coil. Perhaps we're looking at an intermittent bad ground or some other connection. A particularly troublesome part is the harness to the opti. They go bad with age. Speedy, please keep us informed if the problem comes back.

Speedy

Yes, you are right. So I took a look at the first coil I bought to test against the MSD. What they both have in common is that they have painted stator fins. The NAPA part I just installed doesn't have any paint, so I'm wondering if there was a grounding problem because of the paint? I'm going to try cleaning the paint off the MSD where it attaches to the housing and swap it in next week just to be sure. If it works, then the cause will be my own incorrect installation.

01Z28M6

If you can do it - and it is hard to get to them all, check every ground regarding the power-train. Random and sporadic failures can even be caused by a worn ignition switch.

This is why your thread is valuable; many readers will learn from the solution without having to go through all the frustration.