The one problem that is very common with these engines is the crank position sensor going bad. The early symptoms of one going bad is stalling when you come to a stop light. The engine will quit just as you come to a complete stop. the next symptom is the engine will not immediately re-start, may restart after 5 15 minutes. This is new problem for Crossfires since out cars are now getting old enough to see this happen. My old car was a 2001 ML320. Since these engines have been around since 1998 the MB guys are very familiar with this problem.

The sensor is very easy to replace yourself but dealers will want a lot more.