2003 3.0 diesel misfire

[Nwr161282]

ok so I got a 2003 x5 a few months ago and every now and then when idling it would misfire cause the whole car to shake. Once revs went above 1000rpm it would clear and drive perfectly well.

Yesterday when stuck behind a lorry I noticed that there is now a misfire when I'm traveling at 50mph. Revs are between 1500 and 2000rpm. Once over all becomes fine again.

When idling and misfiring I have pulled all the injector wiring plugs off 1 at a time to see if there is any difference. When I pulled off injector 3 wiring there was no note change to the engine so I'm guessing there is an issue with injector 3 but wondered if anyone has had a similar problem and found a solution for it.