My fiat Ducato 2.5d is suffering from jerking under acceleration. I’ve changed the clutch, engine mounts, timing belt and fuel injection pump and it is still doing it. Has anyone got any ideas?

If the fuel pump is controlled by a cable get it checked out for frayed wires and if possible lubricate by running oil inside.
Other idea is air in the fuel, not too much that it has start problems though. Change filter and bleed through, with if possible a clear hose pipe on the line to check for fine air bubbles.