would remove EGR valve and see if it is seized,follow the intercooler hose up from l/h lower side,remove three 30 torx bolts,this gets you access to egr valve which is held on with 3 torx 20 bolts,remove and you will see a spring,push down and see if it returns,if stuck spray with wd40 and get it working back and forward,forgot to say remove fuel filter from bulkhead and swing over on top of engine to gain access to egr.If it is still the same would maybe get a code reader onto it for a look.Another thing to look for is a stretched timing chain knocking valve timing out and tensioner also if it hasn`t had regular oil changes.
wickham
June 2010