I read somewhere else that the fusebox can be issue-prone. I guess I should take that apart and fix it before it has a chance to be a problem.
I was looking for a computer check engine light/equivalent, read through the service manual, and saw no reference to one, so thanks for the confirmation. I did see that there is a special tool needed to check the codes, that's a bummer. I was also unable to find any oxygen/lambda sensors. The fuel injection system reminds me of how some aviation fuel injection systems work, although those generally have exhaust gas temperature sensors, very unusual system here.
I wonder if there has been any effort to reverse engineer the protocol used to run the diagnostic computer? It would be interesting to see if any effort has been made there, or if there's at least documentation somewhere of the commands sent between the computer and the diag tool. I'm guessing the factory tool is rare as hen's teeth and difficult to get ahold of, I'd kinda like to play with one, though. If I could put a sniffer between the tool and the computer in the car, possibly I could make an open source version. Maybe I'll channel some efforts in that direction when I'm done with other projects. I'm currently working on making a digital cruise control module for my 84 mercedes to replace the issue-prone analogue unit.
Are there any other common problems that I should go work on right off? I already changed the engine oil and have transmission oil and differential oil on my todo list. I should replace the plug wires and probably the plugs as a matter of course and, if there's a source for them, the cap and rotor(s?). The only other engine I've worked on with two coils going into the distributor is an RX7, but that's a bit different