Basically you need the engine good and warm, then disconnect the IACV. The idle should be stable at 850. If it isn't adjust the set screw to achieve 850.
Then plug the IACV back in and allow it to settle. It should now have an idle of 875.
Then you may have to complete a throttle position reset. That is ignition on, engine off, press the accelerator to the floor five times, wait 30 secs then turn the ignition off. Start the car and hopefully the idle is stable at 875.