Not sure if this would be it but maybe clogged pcv valve for rough idle? I just recently took a peak in oil filler neck and sludge was really bad. Last time I checked it was fine and then when cold weather hit it sludged up real good. Did an oil change and checked the PCV valve and it was clogged up as well. May not have anything to do with it but mine seemed to run better after replacing PCV and oil change