For about a month my 1991 Nissan(auto , 4x2) would sometimes have a rough idle and sometimes stall as it slowed to a stop. Two days ago it refused to start after a 50 mile trip in which it ran fine. Engine turns over and I have confirmed the plugs are getting a spark. Have new air and fuel filters and checked for leaking vacuum lines. I checked stored trouble codes and got 55 which is normal operation. I have noticed one odd thing however, when I pull the fuse for the fuel pump to take pressure off the lines to change the filter, the engine will start and run until it uses up the gas left in the lines and rail. If I restore power to the pump it wont start. I would very much appreciate any ideas or help!