I am sorry that you are having trouble Chris. This is the best place to get advice for sure. I am just starting to sort out my own project car and have been reading lots of information on the internet about it. There are a number of common problems with these cars. Checking some of the most common ones might help you rule out some things.
The first thing that I would check is the DME relay. This procedure at Clarks Garage will help:
DME Relay Information and Testing
The second thing would be the factory alarm module which has been known to cause problems. This one has info on it:
Alarm System - Bypassing
The next thing would be the reference sensors that tell the computer when the engine is at top dead centre and how fast the engine is rotating. This one has the details you need:
Speed and Reference Sensors - Checking, Replacement, and Adjustment
Clarks also has some general trouble shooting guidance:
Troubleshooting - Engine
My DME relay and alarm module were not my problem, but the reference sensors were. If you find that your reference sensors are the problem, I can point you to the best advice if they are difficult to remove. Mine were stuck, but I managed to get them replaced with the advice provided on this forum. Good luck!