td5 slugish

hi i have 2001 td5 110.it seems slugish it will slowly build up the revs than all of a sudden,go of like a fright train,but its so high in the rev range you cant keep it going.no heavy smoke,serviced by me about a month ago genuine filters.so far have changed injector harness+air maf sensor.anybody have any idears please

Injector washers or dodgy maf at a guess- with engine warmed up unplug maf and if it runs better- you know the issue.

Try giving the MAP sensor a clean