FWIW- The square plastic box is the 'air box' with the air filter and the IAT, aka Intake Air Temperature sensor. I would also check for loose or cracked hoses leading into the the intake, but a bad IAC (Idle Air Control) valve is fairly common. At $80 for a replacement IAC, it's worth a close look at ALL the other hoses to make sure their OK before buying a new valve.
