Ldv maxus van won't rev HELP

Ldv maxus 2.5 diesel VM engine 95bhp 3.2ton
My 56 plate ldv Will start and idle on it's own power, but will not rev past 1500rpm, and then after that begins to knock a little, throwing out a lot of black smoke out the back. Will drive slowly only using the clutch and low rev but won't rev up. The edc light is always on. I have only so far taken off the egr valve, which was stinking and a bit seized, but cleaned up and moving and been put back on but same problem. Anybody have any help or idea? I'm going back to the yard tomorrow to tackle it a different way, like maybe swap the throttle body from another maxus van I have(the same) to see if it that etc, I can only guess at the moment until somebody gives some professional advice/help. Many thanks! Josh