Originally Posted by 90_spec

That's what i have been thinking, its very strange, i would have thought a vacuum leak into the manifold would cause a more constant like revving, its almost like its in a test mode or something,
i was suffering with poor low down throttle control and similar idling, although it would jump from base idle to 2000rpm and kicking quite violently when coming on throttle, so i re-checked the AFR and it was very lean,
After resetting the AFR and fuel pressure it now drives very nicely both low down and through the throttle onto boost, but the constant revving up and down is worrying me, as it will idle very fast when first started.

When it hits 1000rpm, it sounds lovely and with a lambda value of 0.98 which is about 14.7 ish.
I wasn't sure if the ECU needs to re-learn or something after changing the Co pot settings and fuel pressure

I will be taking it to MSD, but that distance a the moment i think is a bit risky, especially if i get caught in traffic with it revving its bits off.