I am posting this in case there is anyone else that may be experiencing this issue with their 300M. This one had 77,000mi. My grandfather's 300M would start and then just stall or it just wouldn't start at all. I hooked up a code reader and it read something about the O2 sensor. I unplugged the connector on the O2 sensor and blew it out and plugged it back in and the car runs flawlessly now. Its not hard to get at. The connector is located on the passenger side on the exhaust manifold and the connector is easily accessible from the hood.

Just thought I'd put that out there. It could be possible there could be some crap in the connector if you are experiencing this issue.