1800 RPM's

I know that slightly earlier Pathfinders had a problem with the airflow meter which would set a code for a lean misfire because the computer in the truck doesn't know the true amount of air entering the engine, that could give you a hesitation. Air fuel ratio sensors, amongst a wide list of sensors could be the cause of the hesitation. Looking at live sensor data on a scan tool while someone else drives the truck is how the problem needs to be diagnosed.