My wife's 89 300se at times begins idling rough and almost to the point of missing. It has 191k miles on it and about 3-4 months ago had a valve job done and the injectors replaced. It does not do it all the time or any certain time. It will be running fine and all of a sudden it will run rough and almost hesitate when pulling out for maybe a minute or two and then it will straighten out and run smooth for a while. I have had a problem with consuming oil(yes, I am the one that has posted about the oil consumption problem) and once in the past I had to replace the plugs due to #2, 3, & 4 plugs getting oil into the hole and fouling it out. #2 was the worst. Could this be a plug problem that maybe fires ok for a while and then misses a few times and then fires ok? Any advise would be greatly appreciated.