ok, i just had a proper good look, and apparently I had it wrong all this time. It's a 1991 body, though I know it won't change much.
 
Can't confirm the SW20 I (JP) or not, but I'd be confident in that it is. Says nothing about it on the ECU, but I didn't check numbers.
 
Another Idea was that when checking the cold start injector thing, it read about 4.6ohms. My other engine was sitting on like 5.7ohms. A friend (Who posted/asked on ae86dc.com) mentioned that if thats wound down too far, it starves it of air, causing it to stall. If I adjust the 93 engine to suit the same ohmage as the 91, would that have any positive affect? Or is it better to just ignore that and go get an ECU? On that note, it says in the BGB that it should read between 2-4ohm. Why is it so much higher to start with?
 
If that option, should I go a nice aftermarket ECU? If yes, any suggestions?
 
Also, I really really do appreciate all the help you guys have been able to offer here. So thanks for taking a bit of time out to write some stuff down for me. The cars been off the road way too long for my liking and sanity, and it will be great to get it running again soon. : )

Yes that screw is on the Gen 2 as well.

Check those things, have a look at your ECU part number... match it with one thats listed in that picture and go from there.
Also, with the diagnostics bridged with a paperclip or wire (as PETE mentioned), see if it idles.
What that will test, is whether the engine is capable of running with all of its sensors at BASE ignition timing. 10 degrees.

Do you still have the other engine?
All of the physical components of both engines will be the same (well... near enough)
you could compare or swap out sensors if you wanted to. Just bear in mind that the TPS will need to be adjusted properly if you do that.