1. Check Electric Throttle Control Actuator Visually

1. Remove the intake air duct.
2. Check if a foreign matter is caught between the throttle valve and the housing.

OK or NG 

OK : GO TO 2.

NG : Remove the foreign matter and clean the electric throttle control actuator inside.

Fig 1: View Of Throttle Valve

Courtesy of NISSAN MOTOR CO., U.S.A.