Sprinter 2005 goes out alone and does not start

Good evening, I have a sprinter year 2005, suddenly the engine began to work, the vehicle was running and the engine was turned off, the entire oil conduit was checked, the start was repaired, the oil filter was changed, the oil pond was taken out of Change it_ (in which part it is located and how it can be changed without going to a mechanic) and with this I will have solved my problem, since it also loses strength and the EDC is turned on on the instrument board, please I need you to guide me since we can not find the fault and if you changing the crankshaft sensor, it will be left for ... Thank you

Hello for me, it has a problem return problem if the fuel was very bad, surely affection for the injectors with just that one fails it is not enough that it is Common Rail Greetings