1. Safety First:
* Park on a level surface, engage the parking brake, and turn off the engine. Don't attempt repairs with the engine running if the throttle is sticking.
2. Preliminary Checks:
* Inspect the throttle cable: Carefully examine the throttle cable for kinks, fraying, or binding. Try gently working the throttle cable by hand (engine OFF) to see if it moves freely. A sticking cable can cause these symptoms. Lubrication might help a slightly stiff cable, but only if you can confirm it's the source of the problem.
* Check for vacuum leaks: Visually inspect all vacuum lines and hoses connected to the intake manifold and throttle body. Look for cracks, loose connections, or broken hoses. A hissing sound indicates a leak. Spray a small amount of carb cleaner (or starting fluid, use with extreme caution) around suspected leak areas while the engine is running. A temporary increase in RPMs confirms a vacuum leak.
3. Diagnostic Testing (Requires Tools):
* Throttle Position Sensor (TPS): This sensor tells the computer the throttle's position. A faulty TPS can cause high idle and erratic throttle response. You'll need a multimeter to test the TPS voltage output at various throttle positions (refer to a repair manual for specifics). Replacing a faulty TPS is relatively straightforward.
* Idle Air Control (IAC) Valve: The IAC valve controls idle speed. A dirty or malfunctioning IAC can cause high idle. You might be able to clean the IAC valve with carb cleaner (follow manufacturer instructions carefully). If cleaning doesn't solve it, replacement is necessary.
* Mass Airflow Sensor (MAF) Sensor: While less likely to cause a *constant* high idle and uncontrolled cruise, a dirty or faulty MAF sensor can contribute to erratic engine behavior. Cleaning the MAF sensor with MAF sensor cleaner (following instructions carefully; do not touch the sensor element) can sometimes resolve issues.
* Computer Scan: The most reliable diagnostic step is using an OBD-II scanner to read trouble codes from the car's computer. This can pinpoint the problem more accurately than visual inspections alone. Auto parts stores often offer free code reading services.
4. Repair:
Once you've identified the faulty component (using the diagnostic steps above), you can replace it. You'll likely need a repair manual for your specific 1997 Ford Thunderbird to guide you through the replacement process. These manuals typically provide detailed diagrams, torque specifications, and step-by-step instructions.
Important Considerations:
* Repair Manual: Investing in a repair manual specific to your 1997 Ford Thunderbird is highly recommended. It will provide valuable diagrams, torque specifications, and troubleshooting guides.
* Professional Help: If you're not comfortable performing these repairs yourself, it's best to take your Thunderbird to a qualified mechanic. Ignoring the problem could lead to further damage.
* Throttle Body: In some cases, the throttle body itself might be sticking or dirty. Cleaning the throttle body can resolve this, but it's more involved than cleaning the IAC valve.
Remember, safety is paramount. If you're unsure about any step, consult a professional mechanic. The uncontrolled acceleration issue is a serious safety hazard and shouldn't be taken lightly.
