I actually had a similar problem when replacing my injectors; it turned out that one of the injectors was defective and didn't let the o-ring seat properly. I took it back and exchanged it for a new one and problem solved! The trick is seat the injectors in the fuel rail first and turn them so that you have only a small amount of resistance in any given direction. As for the filter, did you replace the copper washers on both ends? And did you torque the banjo bolts to stock spec? Both of these will cause it to leak. I'd also check the washer/banjo on the rail.