How do you adjust the idle speed on a 1991 Volvo 740?

To adjust the idle speed on a 1991 Volvo 740, locate the idle adjustment screw on the throttle body. Start the engine and allow it to reach normal operating temperature. Use a tachometer to measure the idle speed, then turn the adjustment screw clockwise to increase the idle speed or counterclockwise to decrease it, ensuring it stays within the recommended range of 750-900 RPM. Finally, recheck the idle speed to confirm the adjustment and ensure the engine is running smoothly.