2006 renault master

please can any one help i iave a renault master 2006 with a 2.5 engine

recently i have had work done to

but i still have a problem , when i start the van i can only get 2000 revs then after ten mins the van works ok

i was told turbo boost sensor was neening replaced of which i have done nothing changed

now i have been that it could be the ERG valve

now can this valve be cleaned or does it need replaced thanks northfielder