The FITV is for when the car is cold. The IACV (Idle Air control valve) controls idle when it is at operating temp. Located on the throttle body near the firewall, it's held on by 2 12mm bolts. Remove the IACV from the TB and clean out the screen to allow it to bypass the throttle valve with air more easily. You can clean with WD-40 or other penetrant. You can leave the coolant hoses connected during this whole time.