UPDATE
The dizzy was fooked, There was a reason this car came with so many parts, the fella couldn't get it running right. It wasn't running right when i bought it but I wasn't thinking straight when i went to buy it I just went for it, paid for it in full without even test driving it first
Anyway - the problems were as follows:
Optical sensor in the distributor was faulty, the spare that came with the car was dead, no spark at all. Sourced another dizzy with a good optical sensor, so thats now sorted. No more cutting out/start issues.
Throttle position sensor alignment was off so throttle was being detected too late. Re-aligned that and now responds when it should.
Wrong distributor cap on the dizzy when i got it, the HT lead connectors were off by around 10 degrees compared to my original nissan dizzy from my old ET, stuck that on now, rotor is brand new too to eliminate any further issues.
Timing was out, cam timing was out by 180 degrees
The wrong timing reference point was used, corrected that, replaced the timing belt with a brand new nissan belt. Now all ok! Compression tested etc to confirm no damage, tested perfect!
Injectors not 100%, replaced injector rail with a good fuel pressure regulator and thats all good now.
ECU consistently throwing no ignition code, traced all wiring and confirmed its all good, tested coil and transistor which didn't measure up properly, replaced the coil and transistor with one i got for my old ET when i picked up the wings down south last year. Even after all of this, still throwing no ignition. Replaced ECU with my one from the old ET, no more error codes!!! For future reference, a manual ECU works fine on an auto.
Flushed coolant, oil change, filter, fuel filter etc. It is now running flipping sweet. Timed up to 15 degrees stock first time after all of this, not cut out a single time, kicks down and pulls so well, love it!
Driven it to work past 4 days, racked up 200 odd miles, average around 27.3 mpg with a little spirited driving which is almost the same as my bmw 320d which makes me think I really need to sort that out too, that should be giving me around 45/50!