I have had the same problem, just got my car back from nissan, it sounds like an afm problem, element could be dirty or connection loose, i doubt you would have the same prob i did but inside the connector box on the afm, some the pins inside had their solder snapped off, they were still touching for a connection but it obviously wasnt giving out enough voltage to get a proper signal to the computer, nissan sent it off to get re-co'ed, the test and reco cost me around $120, but could be fuel pump or even igniter module but probly not, if the fuel pump was on the way out it would make some load whining sounds every now and then, and if the igniter module can be faulty when the car is warmed up
anyways hope this can help in anyway