Well, I replaced the ECU with a non-immob. earlier version, and the car now starts [albeit under full throttle] and runs for about 10mins then just cuts out! No chugging, just cuts out.
I called the auto electrician who advised me that my ECU was shot, and when I described the symptoms, he said it was the hall sender that needed replacing.
What is weird though, it that although I have fitted an ECU that doesnt have an immob. I still need to disable it before my ignition lights come on. This would mean that its actually an aftermarket immob. right?
God I'm crap at this sort of thing!