I am still in trouble here. My mechanic took the car to our Mercedes Dealership, after three days they gave up and gave it back to him, although it turns out that they apparently don't have anybody there who really knows diesels. I have noticed what I thought was a fuel leakage problem in the past, when the tank is below 1/4 full and I park the car on an incline with the front end higher, the car is really hard to start in the morning. I always figured air was getting into the system somehow and letting fuel run back into the tank but my mechanic could never find any evidence of leakage and I never smelled raw fuel in the engine compartment. I will share the fuel line information with him again tomorrow and suggest that we replace the fuel lines.