I just got a P0176 code on my 99' Ranger 3.0L Flex 4X4 offroad. The truck is running fine. Does anyone have any experience with the fuel composition sensor circuit?

Questions I could use answered:
-Where is it?
-Do I need it if I only run 87?
-Can you buy them or dealer only?
-Does this code mean the sensor is bad or bad wiring?