UPDATE
Today I serviced the van, she was well overdue and really quite filthy tbh.
I removed the foam behind the airbox, derestricted the airbox by removing the inlet tube both outside and inside the box base, added a larger intake pipe dorect to the side vent, once this was done I added the Green Cotton Filter.
The almost choked EGR system has now been removed completely and blanked at the manifold with a new smooth flow tophat pipe.
All old Vac Lines have been replaced with silicon hoses, many had been rubbing for ages and very very brittle.
New oil filter and oil, new pollen filter and fuel filter.
Van now drives so much more smoothly and feels more responsive.