Finally its fixed.It came in at the end of November and the customer was told by the dealers that they haven't replaced many pumps so he decided to the the injectors checked.
I did what I was told and took the injectors off and sent them off to a authorized Delphi diesel shop.Two days later a Representative from the shop rang and told me that they were not contaminated but one injector totally failed and another two failed on stage 2 of testing and the last one was ok.I decided to get all 4 reconditioned as this van was starting to get the better of me.I put the reconditioned injectors in ,went for a spin and it was the SAME as before.I rang the delpi shop and told him the van was the same and all the tests I had done .He said that it more that likely was that the pump can generate sufficient pressure but cant maintain it,something about its internal hydraulics heads and that it wasn't the normal fault associated with these pumps.He never answered why the van ran ok up to 3000rpm with 3 faulty injectors.
So last Monday we fitted a new pump from Ford and its flying now.It felt like Christmas had come early to finally see the back of the van.
Thanks for all yer input and sorry it took so long,this was a job that was measured in months rather than hours.Is there a monthly rate.