Tried what Richard suggested with cps all appeared fine but cleaned mounting block and surfaces
anyway , cps checks out with ohm's test.
Have run vehicle with whole exhaust off as a check for Cat problem, will try loosening it though as this may help with required back pressure for good turbo boost.
Had a look at thottle pedal unit this morning too, this works within set limits from autodata, what symptoms did you get with faulty map on transit John?, What age was the van?
Thanks for replies so far, cheers phrom fill.