Hi mate,
Ok.... The other thing that the fault code will relate to is the MAP sensor. Its located at the back of the engine on the manifold just to the left of the EGR valve. The wiring can get knocked on it when you remove the engine cover as it sits a bit proud. Remove the wiring plug and check the pins and plug it back in. If the problem is still there then you can check that the small hole in the sensor hasnt become blocked with gunk. To get at the 10mm bolt which holds the MAP sensor on, you need to move the EGR. You can get away with undoing the 3 13mm bolts and pushing the EGR back a bit rather than removing it all. Again, you can use carb cleaner to clear out any gunk.
As the wast gate is moving ok when accelerating, and after your cleaning, you can probably rule out the boost solenoid (dont worry you haven't wasted your time as a good clean will keep it working properly for longer)
It looks like its almost definately going to be a MAP sensor problem.
Alan