Sounds like limp mode ... when it does it, take your foot off the accelerator completely, and then reapply and see if that is why it is coming back to full power. If it is, then it probably is limp mode, and you need to track down why.....
Your other possibilities are the TPS ( Throttle Position Sensor ) ... this could be dirty, or a little worn and not always getting good contact. You can check this by checking your accelerator pedal for sideways movement, and check the physical connection of the pedal contacts.
http://www.nissanpatrol.com.au/forum...osition-Sensor.
It may be the Crank Angle Sensor, it could be your injector pump, it may be a boost leak, stuck vanes in the turbo, etc, etc ..... I can't see it being the crank itself or anything internal to the engine .... that doesn't make sense at all
