I used RaceTrac Prem unleaded Gas and the Service Engine Soon light came on

It could be a problem with ignition coils or engine wiring harness. Search the net for "Nissan technical service bulletin 01-059" it explains a bit deeper.

Very commom problem with this car...but it is not the fuel....likey ignition coils failing or a wire harness problem. Nissan had TSBs published about this problem. Check on line for bulletins #NTB01-059 & NTB01-076B.