When it came on, was it raining or damp outside? If it was, then it's probably the crank sensor. I have heard of the cam sensors going and it being a pain in the a$$ job. Have you asked anyone at nissanforums.com? They have a lot of experience with the older models. From my experience the crank sensor will cause the engine to not start. The cam sensors can cause it to run rough or stall. I hope this helps.