oil in the injector loom

its fitted but blanked off at the manifold

Could all these problems be associated with a leaking exhaust manifold?

The disco has started to whisstle at idle, almost like an aux belt slipping but goes under accelleration (the belt and tensioners were changed a little while back so i dont think its this thats making the noise). I've had the turbo heatsheld off and all studs are there and there is no obvious sign of a leak.

make sure its not yer belt....at idle put a couple drops o water on the belt.
if it was a exhaust leak, specially at the turbo, u wud hear it when driving. ave u checked yer hoses on the inlet after the turbo....they sometimes crack & flake on the inside. is yer waste gate on the turbo mechanical or electronic?

the wastegate is controlled by a mechanical arm connected to the wastegate control module down behind the a/c pump

the comment about it going into limp home mode might be right, as i stoped off for diesel tonight is was running as it always does, then pulling out of the petrol station it went like a rocket for 5 min before returning to normal