I love this write up and now, I'm now going to do the unforgivable, ask for advice, even though I've read and re-read the dirty dozen. The problem is so simple. 97/98 ZJ that loses it's settings, or so it appears.
Starts running like a dog, stalling every time you slow down, basically showing all the symptoms that I once would have ascribed to a blocked idle jet. Take the battery terminal off, leave for a few minutes, re-connect. Problem solved, for a few weeks.
Now, taking a battery terminal off is not hard. Every few weeks is not too big a deal, but now it's every few days and I can see where we are heading!
This is a RHD vehicle and the black boxes are out there in the open. All looks really solid and so far wiggling hasn't indicated anything. At first I looked at battery terminals and earthing points but I've worked through those. I'm wondering about a cracked solder joint somewhere in the brain but tracking that down is an escalation of the campaign so I'm asking for help from anyone who's had a similar problem and nailed it?!