Hello all,
Just to share my experience with intermittent reduced power.
Initially It started when accelerating from roundabouts, it was a complete pain because I live up a steep hill, so on the way home I would end up crawling up at 15mph.
Once stopped for 5mins and restarted, it seemed fine. It logged no errors at all on my iid tool.
I purchased a OEM VDO maf/map sensor, it made no difference.
I then cleaned the air induction side, the issue got 10 times worse.
Bad news that it was worse, good news, I now knew the issue.
A cracked inlet manifold was the issue, the cleaner had exposed the crack allowing more air in, causing an In ballance on the sensors.
New inlet manifold and the car is running fantastically, even gaining 2mpg better.
Hope this may help anyone else with the same issue.
Shepp[/list] MY12 RRS HSE
Gone 4.2 supercharged RRS
Gone 90
Gone s2000

Common fault

Unfortunately it is, but unfortunately there are a few common faults to choose from
Doesn't help that the inlet manifold is some cheap plastic rubbish. MY12 RRS HSE
Gone 4.2 supercharged RRS
Gone 90
Gone s2000

Sadly, "cheap" is one thing the inlet manifold isn't. BTDT paid the bill.  2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed