smokey L322 engine

Hallo,
I own a 2002 diesel L322 range rover vogue that has recently lost power, become sluggish and is now smoking considerably especially uphill. Strangely this started almost immediately after its last service where we had changed air filter, diesel filter and oil filter. Anybody have any idea what this could be ??

sounds like a intercooler pipe has come off, or has a split in it