Cold start : cuts out after ~7 seconds. Did this once every few months, but now totally dead.

One factor landspeed has mentioned gets my attention: the vehicle is operating (barely) without a catalytic converter. There are sensors fore and aft of the cat, so I would suspect something is going on with the exhaust system. I think that would account for many of the symptoms described.

As for the MAF sensor, just because it looks clean doesn’t mean that it is!

 

Yep; the forward sensor is a requirement, the aft is the feedback loop to manage electronically controlled fuel mixture. The ECU will run the engine for a bit on base factory settings - then it should throw codes and possibly throw it into limp mode. Don't know how they have it wired up to spoof those sensors.

 

I bailed from this after giving my advice, which was essentially the same advice you've received multiple times now. I would add that there are gas tanks available here in the US from dismantlers, most of which are in California. Check car-part.com to find all of those. I've replaced the tank in one of mine with a used tank and haven't had any new problems.

Just because you get some gas from the pump doesn't mean you get enough fuel pressure to not cause problems. And, did you check the fuel filler neck like I told you. Maybe you don't have snow, but these are old cars and it could still be rusted through. Literally takes 30 seconds and no tools to eliminate that as an issue.

I also am leery of advising on the early Japanese models. Not sure how different they may be, especially the ECU software.

Otherwise, you seem to simply have typical ICE issues. Do you have a service manual so that you can follow standard diagnostic procedures? If not, go to http://www.charm.li and download it. They only have the 2001 and up manuals, so again, not sure any differences with your Japanese model which may have come out before that.