Since it also sputters when trying to drive, the problem is not "low idle". The idle rpm is probably normal but the engine is misfiring so badly that it shakes and stalls.

Disconnect the fuel injectors one at a time to see if the problem is isolated to one bad cylinder. When you disconnect a good cylinder, the engine will stumble and get worse. Disconnecting a dead cylinder won't change anything.

The ECU uses feedback to the IACV to keep the idle speed at the programmed value. Turning the idle air screw is immediately counteracted by this feedback, so the speed doesn't change. That is until the range of the feedback is exceeded. The proper way to adjust the idle air screw is to open the feedback loop by disconnecting the IACV. With the engine warmed up, adjust the screw for a very low idle, until the engine almost stalls. Reconnecting the IACV will then establish a normal idle. This of course assumes the engine is not misfiring.

 

As usual, mk makes an excellent point. If any fuel injectors are proven bad by mk's test but they are making the proper clicking sound, then a Seafoam treatment may be worth trying (see forum DIY section).