What adjustment might be needed if an engine is idling too high?

When an engine is idling too high, adjusting the idle speed is directly relevant to bringing it back to the manufacturer's specified idle RPM. This adjustment can often be made through a simple screw or electronic controls in modern engines. Additionally, checking for vacuum leaks is crucial because leaks can introduce excess air into the intake manifold, which can cause the engine to idle faster than intended.

Addressing these two factors—idle speed and vacuum integrity—ensures that the air-fuel mixture remains balanced, which is essential for stable engine operation. Any imbalance may lead to performance issues or even engine damage over time. Consequently, this answer encompasses the primary and most immediate solutions for correcting a high idle condition.