Not to beat the dead horse, but I have the exact same scenario with my 1991 Legacy L 2.2 Automatic. Then it went away for a month, then came back to stay. It was throwing all kinds of codes... too many to make any logic, but swapped the plugs, wires, fuel filter, and O2 sensor, figuring that these things would need to be done soon anyway. Also, pulled all the injector electrical connectors, cleaned them, and put NoOx in case (cant hurt). Only code left is 15 for injector #2 Abnormal Signal... Considering buying a new injector or a whole set..