I have checked earths all over and have upgraded the earths to significantly larger wire and better connectors during the build - cant seem to find a problem on that side of things. I've even gone all over the engine/gearbox checking continuity with the chassis and again everything that should be earthed checks out.
Think I'll get a replacement ICM ordered up, might even get another new distributor cap and rotor arm just to completely rule out that the new ones have a manufacturing fault (think this is really unlikly but beginning to pull my hair out now)
If the new ICM doesnt fix it think I might have to get it booked in somewhere, work is severly restricting the time I have to spend on the car at the moment and I'm running out of ideas. Think I might have to reluctantly resort to booking it in somewhere....not sure who I'll trust with the car...Performance Autoworks is probably top of my list simply due to the reputation and feedback I have read on here....will need to book a day off and another transporter to get the car there though

If its going somewhere like Performance autoworks I might be tempted to have a few more things done while its there, maybe an ECU upgrade and proper mapping...this could turn into an expensive little fault!