What should I do if the idle speed of Subaru Forester 07 2.0 is unstable?

Unstable idle speed of automobile engine refers to the unbalanced force in the cylinder of automobile engine, which causes the piston to collide when doing work, causes the engine to shake and makes the idle speed deviate from the normal standard range. Engine idling instability is the most common fault in engine maintenance. Cause of unstable idle speed of engine: 1. Air leakage in the intake pipe. If the intake pipe leaks air, it will make the gas inside the engine out of balance, make the pressure too high or too low, and thus cause the car to idle unsteadily. Please check whether the vacuum tube and the intake manifold are leaking, and whether there is a problem with the canister valve @20 19.