Cylinders 5, 7, 8 not firing, ignition coils good but no spark?

Hi. This truck was running perfectly fine previously. It sat for about 1 year as it wasn't needed for that time. When I went to start it, it had a terrible misfire.

I have checked and can see 12V on the wires to the coils with the ignition on.

I isolated the misfires to 5, 7, and 8 -all but one cylinder along the right side of the engine. I have been able to run it while diagnosing by first disconnecting the fuel injector harnesses to try and minimize the amount of unburnt fuel. But to be clear, I disconnected fuel injectors while the engine was running and there was no change in engine speed.

I got an old school spark tester and put it in-between the COP pack and -well- I couldn't reliably get it on the plug, so I grounded the other end to a steel bracket on the engine. Started it up and definitely no spark. I only did this on CYL 5 but given the similarities I believe 7 and 8 are experiencing the exact same issue.

I swapped coil packs between cylinder 1 and 5. The coil pack from 5 worked perfectly on cylinder 1. The pack that was working on cylinder 1 is not working on cylinder 5.

I took a (cheapo) oscilloscope and back probed on cylinder 5 harness with it connected to the cylinder 5 coil pack. 12V at one side (engine running), and the other side showed activity but it was more like spasms than a "pulse" like you might expect. I looked at the same on cylinder 1 coil pack and got a fairly clear waveform more like you would expect to see.

But that's where I am now stuck. I don't have wiring diagrams or other information handy to know where the wires trace back through the loom. I don't know if there is any point in which the wires from the PCM to the coil packs for cylinders 5, 7, and 8 might be near one another or feed off a shared ground, etc. Is there a bulkhead connector I should check? Where is the PCM located and how is it removed?

I'm fairly handy with these kinds of things but I'm used to VWs, Hondas, and Toyotas more than this Ford.

Any help or suggestions you can offer are greatly appreciated. It's my mom's old truck and she wants to sell it since she hasn't been using it, but if I don't get this figured out or find someone who wants to take it on as a mechanic special, it's going to be recycled. Shame to do that since even the AC still works as well as the 4WD.