Why is the idle speed unstable after the valve clearance of Wuling Wangxing engine is reduced?

In the first case, the valve setting ratio is really small, resulting in the intake air volume is too small, but the oil supply is appropriate, but because you set it too small, the intake air volume is too small, so the oil is more than the intake air volume. The combustion will be insufficient, and the power given by the piston is coughing. Idle work, less air intake, less oil, enough air intake at idle speed. After turning it down, you want it to inhale less air than when it is idling. Do you think it will be stable? Oil supply system, please check the fuel injector and oil supply pressure.