I have a W140 500SEL. I recently added a bottle of Mobil Injector cleaner to a 3/4 full tank of petrol. I notice that the car run rough at idle after half a tank of petrol.
I suppose it is not all that bad but it used to be smooth that one cannot detect any vibration from the engine.
Could it be possible that the injector cleaner clean the injector and make it runs rough?