The only problem I have had was the Crank Positioning Sensor. (CPS) And will advise you to get a spare Bosch (only) Brand to keep with you along with the needed tools. Within a month of buying my car I had found this forum and started reading up on about everything I could find. Pulling the RCM and checking the joints was probably one of the first things I did, and they were fine.

Simply rule for knowing which one is most likely the problem:

RCM
Engine dies - everything works when key turned - nothing when turned to starter engagement - car cools off and works like nothing was wrong. This is normally the case with the RCM, you do have multiple relays on the board - fuel pump relay also.

CPS
Engine dies - everything works when key turned - starter spins but no start. Car cools off and starts up.
Chances are you will get a check engine light, But not always.