How to solve the unstable idle speed fluctuation issue in Focus?

[RonanLynn]

When the idle contact point is disconnected, the ECU determines that the engine is under partial load. If the engine speed does not increase when the air conditioning is turned on at idle, this can confirm the fault. Oil contamination and carbon deposits can cause the idle control valve to operate sluggishly or get stuck. Clean or replace the idle control valve, and use a dedicated decoder to perform a basic setting of the idle speed. When the opening of the idle control valve increases, the intake air volume correspondingly rises. If there is a leak in the intake pipe, the intake air volume and the opening of the idle control valve will not strictly follow the original functional relationship. If a hissing sound from the intake pipe is heard, it indicates a leak in the intake system. Locate the leak, reseal it, or replace the relevant components.