NF Mod/Nissan Master Tech
2006 Pathfinder LE, 2003 Frontier SVE
Since it appears that the engine is running rich, the first thing I would do is check to make sure the vacuum hose is attached to the fuel pressure regulator at the back of the engine and then test the fuel pressure with a fuel pressure gauge to make sure it is within specs and not excessive. Also, make sure the coolant gauge needle is about in the middle when the vehicle is at normal operating temperature. If it is sitting at the lower end of the gauge, near the "cold" range, you may have a thermostat stuck open that needs to be replaced. If all is good at this point, definately look at the ECT sensor and make sure it is reading correctly and the circuits are good.