When I originally repaired the car (before I actually bought it) it started and idled fine!

The back story for this car for anyone who's interested....

To try to explain it should be noted the previous owners didn't understand a lot about cars and something would only be repaired if totally necessary to just get the car running. Unfortunately prior to bringing the car to me to repair they had been taken advantage of by various garages and dealers and various things had been replaced that I don't think were necessary (including the shoddy job on the loom)

So after I got it running I took it for a run and noticed that oil was mixing with the water. I told them about this and that it would need further investigating which I would do for about 50€. They decided not to do this and took the car back and drove it against my advice. At this time i suspected a head failure but couldn't rule out the oil cooler being at fault. I offered a compression test and to see where we go from there.

After they drove for a few weeks and in this time they had to buy a new radiator and new gear oil as the gear oil was mixing with water inside the rad. This was only repaired as the gears would not engage.

The car then ran fine for a few days with one episode of this revving problem which cleared away. After two days the oil cooler (in their words) exploded therefore this was also replaced.

Since then every time they tried to start it it's on full throttle revs.

I didn't do the work on the rad or the oil cooler which I can only presume is because they felt silly bringing the car back to me when I'd expressly told them not to drive it until we had diagnosed the oil in coolant.

So they then decided to give up on the car completely, got to a point where they needed some cash and offered it to me.

I did a compression test which was fine and accepted. My intention is to repair the car properly and let the wife use it for the school run etc. Therefore I intent to do it properly.

I have the Carsoft system which isn't the best. It's bringing up codes about various things but nothing that I can see that would be related to this revving. MB won't run it through their star diagnostics as it currently doesn't have a MB loom. I live on a small island and only the MB dealer has the STAR system. I think if I can get this runaway problem sorted I'll have to invest in a STAR system as I'm not a great fan of Carsoft.

Thanks again for all the advice. It's greatly appreciated and I'll post back once I've tried a few of the things recommended.