I have a 2015 ATS, 3.6, AWD. I have read several posts on the forum about rough idle. I'm having this issue also. It's not to the point of annoyance, but enough to be noticeable. My car idles, after warm up, at 500 rpms' which seems a little low to me. I was wondering if this might be a contributing factor. Can anyone here tell me the recommended idle speed. Thank You