why does my Ford F-150 have an unstable idle when in gear?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety during repairs.

2. Clean the Throttle Body

• Tools Required: Throttle body cleaner, soft brush, rags
• Remove the air intake duct connected to the throttle body.
• Spray throttle body cleaner inside and use a soft brush to clean the throttle plate and surrounding areas.
• Wipe off any residue with a clean rag.
• Reconnect the air intake duct.

3. Inspect and Clean the IAC Valve

• Tools Required: Socket set, IAC cleaner
• Locate the IAC valve, typically mounted on the throttle body.
• Remove the IAC valve using a socket set.
• Clean the IAC valve with IAC cleaner to remove carbon buildup.
• Reinstall the IAC valve and ensure it is secured properly.

4. Check Vacuum Lines

• Tools Required: Visual inspection
• Inspect all vacuum lines connected to the intake manifold for cracks or disconnections.
• Replace any damaged vacuum hoses with new ones.

5. Test Fuel Pressure

• Tools Required: Fuel pressure gauge
• Connect the fuel pressure gauge to the fuel rail service port.
• Turn the ignition key to the "On" position (do not start the engine) to check baseline fuel pressure.
• Compare the reading to the specifications for the F-150 (typically 30-45 psi).
• If pressure is low, investigate the fuel pump or filter for issues.