So just a bit of an update
Since last time I've done extensive checks for vacuum leaks with butane gas and found nothing. I saw that I had a small exhaust manifold leak on one of the corners so installed new gaskets on the engine and turbo side just to make sure the lambda wasn't reading air from outside and throwing the AFR off.
I've also got the DET3 to send a WOT signal to the ECM as boost builds so got full control now and the wastegate actuator is now plumbed to the intake manifold so the boost goes from 0.43 to 0.37bar - both worked a treat and happy with the outcome!
Next step regarding the vacuum leak was to try isolate all the piping coming off the intake manifold one at a time and see if that made a difference, the only one was the EVAP line which once clamped seemed to make the car idle much smoother and the STFT also seem more stable so I decided to take a drive and see how things were while clamped.
The car drove smoother and the rev hang got a LOT better but still not quite as it was before, the biggest thing that happened is boost suddenly shot up and I hit an AFR of 14:1!!
I quickly let off the throttle and luckily all is ok!(I've now added fuel to compensate) So I've been driving 2 days with the EVAP line clamped and no CEL which is weird and the rev hang seems to be getting less and less but will only see in a couple days - Think the ECM is learning...might need to do a reset.
So I'm off to my homelands, SA from Thursday so won't be able to do anything more for a couple weeks, I suspect the EVAP valve is stuck open so I'll order up a new one once I'm back.
Hopefully this is the problem!