The story so far.
Still cutting out, after talking to people about it at Rockingham i tried lifting the cover over the ECU to cool it down a bit, no joy with that. Checked the wiring to the de-perk fan and the engine earths, they are fine and show nearly no resistance. I took it for a good spin in the hot weather yesterday and when i got on some country lanes with the engine up to temperature it progressively got worse. I listened carefully to see if any relays were clicking when it was doing it and couldn't hear anything, the fuel pump relay certainly wasn't making any noise.
Not sure if this is any help, but no lights come on when it cuts out. I would of thought if it was an ignition or ECU problem the ignition lights on the dash would come on? As if the ignition switch was being turned back a click and causing the engine to stop.
It still seems worse while going round a right hand bend, i intensionally went round a fast right hander to see if it happened and as soon as i turned in at speed the bloody thing just died and cruised round. I kept the throttle in the same place all the way round and as soon as i came out of the corner it came alive again!
Never did it going the other way on the same bend!