Engine revving uncontrolably

Hoping someone can help,

Couple of weeks ago my V50 2.0D had what i thought was a diesel run away. After a quick once over fault couldn't be found and was assumed to be turbo failure. I decided time was enough to get rid and put it up as spares or repair. But since then one of the mechanics has a bit of down time while awaiting new rollers for the dyno so had a bit of a look see at the volvo.

The symptom seem to be that as soon as it starts (which its very reluctant to do) the revs go mad and it sits revving its nuts off, was assumed to be oil getting in as even if you turned to off with the key it kept going. Since then its been found that if you unplug the injectors it shuts down and its only when the final one is connected it goes nuts. It's also showing up multiple fault codes.

Has anyone come across this? we're thinking it may possibly be an ECU fault?