Fast Idle Control Device (FICD) Solenoid
WARNING: This page is about a different car, the 1998 Infiniti Q45 and 1998 Infiniti I30. However, it is still accessible from the selected car via links, so may be relevant.
Disconnect FICD solenoid harness connector. Briefly apply ground and battery voltage to solenoid terminals. Solenoid should click as it is energized. If solenoid does not click, remove FICD and check for seizing/sticking plunger or a broken tension spring.