hi guys. quick update.
Last night I disconnected the plug off each injector, and then fully disconnected the battery.
Left it overnight, then reconnected everything in the morning. My hope was that the ECU may reset itself and help in some way. I also removed both CAC hoses to thoroughly check for splits etc. Nothing, all good. One thing I did notice was that the clamp on the inlet hose on the engine/turbo side was loose. All back on and tight now though. I also noticed that the oil separator pipe on the CCV is split

But I can't see that being an issue when driving, more on tick over i'd have thought.
Also pulled my MAP sensor and cleaned it. Then I bled the fuel system thoroughly and tried starting it up. Took a few attempts, but eventually went. Let it idle for 20 mins. Whilst ticking over, I listened to each injector to make sure they were working ok. They are. Switched it off after 20 mins, let it sit for 1 minute, then tried restarting again. It cranks for ages then eventually fires.
My suspicions are now more than ever a dodgy MAP sensor. Anybody else agree?