Well i got under the car today(with oil smudges all over my face afterwards!) and i found where the oil was coming from. It was the hose that comes from the air intake side on the turbo was half off and the jubilee clip loose on the samco hose. I have tightened it the best way i could, it seems as you tighten it it pulls away from the turbo which isnt very good, but for now its secure enough....
I suppose it would explain why i was losing power sometimes because if it was sucking in air there the MAF would be getting a false reading ie: less airflow through the MAF, however not sure that it would explain the "negative deviation" fault as the the intercooler hoses to the turbo seem nice and secure.