ETM V50 2011 2.0 L Petrol Powershift

Hi all, I bought a 2nd hand V50 2011 2.0 L Petrol Powershift with 198000 km on it, the other day. It is still in an exccelent condition for a vehicle this old with so many kilos. I got a problem after I did an oil and spark plug change, because I did not get a service record with it. Does anybody know what this "bolt" is used for on the Electronic Throttle Module (please see attachments). Why I am asking is that my vehicle is idling high (after the "service") and I cannot find anywhere on the net or the manuals that I bought, a description of how to set the idling on this model. Or is it controlled by the ECU and can only be changed through a computer coupled to the OBD. I do not want to "screw" around with this "bolt", but if I do not find an answer in the near future, I am going to try my hand on it anyway. Unfortunately for us in South Africa, the service centres for the vehicle are far and between and the charge exhorbitant prices for labour and parts. The current idling speed is between 1200 and 1400 rpm and it is "eating" through a fuel tank in no time. Hope anyone out there has an answer or suggestion. Greetings from a sunny South Africa, Feetloose.