2005 cummins qsb 5.9 fuel pressure

port engine lost power recently after an outstanding summer of run time. error message on new SMX display popped up.

I replaced fuel filters and racor filter elements. Port was slightly darker than stbd filter.

Stbd engine runs fine, westerbeck gen runs fine.

Port Fuel filter full.

Bled injector lines fuel leaked out but did not spray out. looking for suggestions.

got several opinions, 

1. bad injector causing lack of pressure
2. injector pump solenoid bad
3. fuel rail sensor

any help appreciated