I'm thinking this might be classic case of bad cam position sensor - they can get intermittent like you described.
Question: Has your cruise control been acting strange lately in that it will randomly turn itself off and not work again until re-start? The reason I ask is that it has been observed that the problem with the CC turning itself off just prior to the cam position sensor getting intermittent and eventually failing. Somebody on the 300M Enthusiasts Club forums made that observation a few years ago, and after he did, others, including myself, recalled having had that sequence of events happen. If you haven't had the CC problem, it doesn't mean the sensor is not bad, but if you have had unexplained problems with the CC in the recent past followed by these cut-off episodes, it's almost guaranteed that the cam position sensor is bad.
It is recommended to replace the crank position sensor at the same time. Many suggest getting the sensor from the dealer rather than in aftermarket.
Question: Has your cruise control been acting strange lately in that it will randomly turn itself off and not work again until re-start? The reason I ask is that it has been observed that the problem with the CC turning itself off just prior to the cam position sensor getting intermittent and eventually failing. Somebody on the 300M Enthusiasts Club forums made that observation a few years ago, and after he did, others, including myself, recalled having had that sequence of events happen. If you haven't had the CC problem, it doesn't mean the sensor is not bad, but if you have had unexplained problems with the CC in the recent past followed by these cut-off episodes, it's almost guaranteed that the cam position sensor is bad.
It is recommended to replace the crank position sensor at the same time. Many suggest getting the sensor from the dealer rather than in aftermarket.
