From what you describe you have a bad fuel injector, the injector is causing the motor to miss just enough to cause the sensors to send a fault code. Nissan recently did a injector body warranty recall and we ended up doing nearly 65 trucks in our area. If you have another unit available with the same motor, swap them and try it before you order one. Any Cat, Nissan or Mitsi with a K21 or K25 will work, even the new design,only diffference is a shorter wiring harness.