Crank, no start!

I have my friend’s Lincoln Continental 1993, 6 cyl, 3.8l, with a crank, no start problem.
Thanks to you guys I can do some diagnosis, but only so far…
I have fuel pressure, I have spark, it starts on start gas, so I have compression, I have 12V to the injectors, but no pulse. I did have a pulse at a crank attempt once, my incandescent probe lit up for a second and the car made a start attempt and then died. I have no idea why this suddenly happened, I haven’t been able to replicate it.

The funny thing is, I drove it home from the last car mechanic who gave up on it. Now it sits on my driveway, dead… I know it works fine when it runs, it’s in very good condition considering the age and most of the electronics work!

The only other thing I’ve done on it is replacing the old air suspension in the rear to conventional springs, it was already done on the front, but I can’t imagine that has anything to do with this.

I’m enclosing a picture from the wiring diagram showing the ECU that feeds the injectors. I would like to think the computer lacks an in-data of some kind, but I can’t figure out which one or ones, I can’t find a crank sensor or a cam sensor. I’m stuck...