For the past 2 weeks, my car has started over revving when idling and the revs are erratic whilst driving too. Have checked the ICV, which has not resolved the problem. The vehicle did this approx. 2 years ago and a dodgy backyard mechanic told me he had replaced a part (the part he showed me did not look the same as the ICV I replaced in this instance). The problem appeared to have been resolved then started up again a year ago intermittently. I'm at my whits end.