I was driving my 05 crossfire to work and it died on me, now it just cranks but will not start, I'm reading allot about the fuel pump relay, i pulled it out and resodered the relay, the car started up for a few seconds and died, what do you all think?

 

Three things are needed to run, air, fuel and spark . Rarely is it a lack of air more often it's a lack of fuel or Spark both of which the RCM manages. But just to verify that it is not a crank position sensor problem caused by either being faulty or a bad connection reach down and unplug the CPS connector and spray with contact cleaner let it dry and then put a dab of Dielectric grease on it and reassemble. Next because it is such a common problem with Mercedes as well as the crossfire I would purchase a new RCM and send the old one to DJ let him refurbish it and when you get it back put it in the trunk for a spare. There are more detailed diagnostic methods available here on the forum but what I gave you was the condensed version.

 

Crank and no start is usually the crankshaft position sensor. Check to see if she has a fault code as the CPS throws a code. The fuel relay could also be an issue.
Turn the key to the ON position.
As soon as you turn the key on you should hear the fuel pump run for a couple of seconds.
Check for codes and report back.