I did a search for "E320 engine missing iddle", but did not come up with anything useful.

My 96 E320 has low mileage (39k miles or 63k kms), and is driven only once every couple of weeks on weekends. Lately, it has developed an annoying problem. It starts and runs very well, but sometimes will miss a beat while stopped at a red light (enough to register on the tachometer). It has done this 3 times so far, twice when the engine is still cold, and once when the engine has warmed up to normal operating temperature (daytime temperatures here in Edmonton, Alberta, Canada is near freezing this time of year). Does anybody have an idea what might be the source of this problem?

Thanks