might be better getting over to rsoc and asking on their mate, they can have idling issues if they have a dumpvalve fitted and its not a recirculating model! also the iscv can do the same, have you had any changes made to the car recently? as the car sometimes needs to learn what its idling point is, normally you disconnect the battery for about 30 mins then reconnect it start the car and turn everything on! lights aircon anything that draws a current and then wait 15mins and then take it for a spin and hopefully it should be ok!