Fuel Injection problems of the 2004 Subaru Impreza

The "check engine" light has come on 7 times since the vehicle was purchased new in January 2004. The first two times I was told by the dealership (valley Dodge, inc. ) that it was a false code (#p0301) for a 1st cylinder miss fire. On the third time the "check engine" light came on, the dealership removed the ecm and sent to the Subaru of America, inc. Factory to reprogram. The fourth time the dealership, per Subaru of America, inc. Factory, adjusted the #1 cylinder exhaust valve. The fifth and sixth time, the dealership per Subaru of America, inc. Replaced the injection and still have the car to beta test on a 100-mile 'test drive' as I was told to compare the read-outs from the ecm during this 'test-drive. ' I have been without the vehicle for 20 days non-consecutive in the 6 months that I have owned the vehicle.