Thanks Shazaam for the education, and Yella for the advice; now stored in long term memory for future reference. I will keep the throttle bodies in mind as well as adjusting my idle mixture in the ECU unit.

I managed to get hold of JHP and I have explained the symptoms in great detail, they seem to think it's related directly to the chip itself - can't argue with the experts.

I have ordered a replacement chip which will be programmed and sent out to me on Monday. Thanks to Rattler for JHPs number - your a star!