I wish I could do more. Im not a mechanic but ive been around these cars for years, plus ive read the service manual a time or two and have some basic understandings about areas to troubleshoot for certain thigns.
it just sounds like you have some electrical issues that's really causing your dilemma, and thats difficult to diagnose over the internet.
someone else on another forum had an issue with engine hesitation/surging. nissan told them it was related to the ECM and a specific harness. one poster suggested to check the harnesses and clean them de-tox the dirt/debris off , whilst I suggested to check battery, cabling, and alternator.
the ECM trick really involves timing, so if you have the procedure (its avail on this forum or you can search the interwebs), you may need a stop watch or something to keep time.
but again, i think its electrical so check your harnesses at the ECM....