So, Ian and Andy kindly popped round today to lend a helping hand and the great news is that we have managed to solve it!! :clap:
After cleaning many connectors, changed the MAF (twice) and the thermostat.... its turns out it was the CAS all along... Running sweet now:)
Can't thank you both enough for your time today, just happy your time wasn't wasted in the end!
A big thanks to Lee Dent again for offering to send me a new one in the post:thumbup1: