That's the way Andy. I reckon the problem is the lines but since reading Aiden's post that makes sense also, just one thing though. If it is leaning out at 5000rpm would that be where the turbo is making enough boost to exceed the fuel pressure? I've got my money on fuel lines though.
Perhaps Dan Gyles could lend you an electric fuel pump. He may have one lying around. I'll ask Scott today if he has one.
Are you hanging onto that Weber adapter plate off Aiden's engine? If so are you willing to get rid of it?