I don’t know how much further you have got with this, but I would support the possibility of crud being picked up by the filter in the swirl pot. On one of my cars, it went from running well to cutting out after 10 mins idling, a time that got progressively shorter until the symptom became start and die. A friend had a suggestion based on experience with his car and a racing XJS. Both ran faultlessly and would then die. He pulled out the swirl pot, found it with a lot of crud and the filter almost completely blocked. Did a clean up and new filter and the problem went away. I pulled the swirl pot out of my donor wreck and found the same issue.

Not for my car, though. Cleaned the swirl pot and replaced the filter to find out, finally, that the ECU was not switching the fuel pump back on after starting. Replaced ECU and car runs without missing a beat. The point here is that the ECU was progressively breaking down from intermittent fault to permanent.

I hope your problem turns out to be the filter.