Best is to remove the manifold and give it all a good clean but I think getting it off is a real pain

I used some degreaser and a flat head to drag most of it out and a rag just be  very careful not to push it into the manifold or could cause serious problems

Also when finished tack off the battery for a while to reset the ECU

Thanks Dave I’ll get some degreaser and have a go at it sometime this week/weekend 

Don't go mad with the degreaser just maybe one spray at the start as the gunk is quite sticky I used a long flat head drag it out and wipe it on a rag you can't see in so take pics as you go and you will see how much you are removing

When you have removed the big bits use a microfiber cloth and a bit of spray to get the rest 

Don't push it back into the manifold as can cause serious problems with the turbo 

Also don't forget to take off the battery for a while for the ECU resets

Good luck