How to improve the idle speed of Subaru's old Legacy electronic throttle?

Steps to improve the idle speed of Subaru's old electronic throttle:

1. First unscrew the throttle, adjustment screw makes the engine reach the lowest stable speed, and then put the screwdriver on the idle screw.

2. When the engine is about to stall, slowly unscrew the idle screw with a screwdriver to make the engine run stably and reach high speed, and then unscrew the throttle screw to minimize the engine speed from high speed.

3. Then unscrew the screw to increase the engine speed, repeat this process until the throttle opening is minimum, and then suddenly close the throttle.