car runs then when shut off cranks but wont start?

What is your question?

If idelling the car will shut off and not start. It does start after leaving it for an hour or so. The check engine light is on. Mass airflow has been checked with no luck. Ideas? Fuel pump or relay?

What makes this problem better or worse?

same

How long has your 2003 Mercedes-Benz C320 had this problem?

a few months