I found out what it’s not…

First the good news:

So, it looks like it’s not an issue with engine internals at this point.

I also put my spark tester on each coil output and cranked the engine, getting good spark on each cylinder.  I was considering 5 different causes, and this has ruled out two of them (blown coil, blown head gasket).  The other three are less likely (loose wiring, blown ignition transistor, something blown in megasquirt), however, it could just be that they’re jiggled together right now and a good hard shove will break it loose again.

The plugs are shot, so I’m going to get new ones, put the old ones in to see how it runs, then put the new ones in to see if that makes the difference.  If not, I’m going to look at injectors, fuel filter, and fuel pump.

In other good-ish news, it looks like Stinky may not have a blown head gasket.  One of the cylinders reads slightly lower compression than the other three, but it’s within 10% of the highest compression.