Mechanical Issues:
* Worn or Damaged Throttle Cable: This is the most common culprit. The cable could be frayed, binding, sticking in its sheath, or even broken, preventing it from returning to its idle position. Inspect the cable's entire length for kinks, fraying, or stiffness.
* Sticking Throttle Plate: The throttle plate itself (the butterfly valve in the throttle body) might be sticking due to carbon buildup, corrosion, or damage. Cleaning the throttle body is often the solution here.
* Vacuum Leak: A leak in the vacuum system can cause the throttle plate to remain open. This is less likely to *completely* stick the throttle, but could contribute to an erratic or unresponsive throttle.
* Throttle Position Sensor (TPS) Failure: While less likely to cause a *completely* stuck throttle, a faulty TPS can provide incorrect information to the engine control unit (ECU), potentially leading to unintended acceleration. A bad TPS would more likely cause erratic idling and poor performance than a completely stuck throttle.
* Return Spring Failure: The spring that returns the throttle plate to the idle position could be broken or weakened. This is a relatively simple component to check.
* Damaged Throttle Body: In severe cases, the throttle body itself might be damaged or warped, preventing the throttle plate from closing properly.
* Interference: Something might be physically interfering with the throttle linkage or cable, preventing it from returning to the idle position. This could be anything from debris to a broken component.
Less Likely, but Possible Issues:
* Cruise Control Malfunction: A malfunctioning cruise control system could theoretically keep the throttle engaged, though this usually results in a more gradual, controlled acceleration rather than a sudden sticking.
* ECU Problem (rare): While unlikely to directly cause a stuck throttle, a severely malfunctioning ECU could send signals that keep the throttle open. This is usually accompanied by other significant engine problems.
Troubleshooting Steps:
1. Visual Inspection: Carefully inspect the throttle cable, throttle body, and surrounding components for any obvious signs of damage, wear, or debris.
2. Throttle Body Cleaning: Clean the throttle body thoroughly with throttle body cleaner. This often resolves sticking issues.
3. Throttle Cable Lubrication (with caution): Lightly lubricate the throttle cable sheath (use a cable lubricant designed for this purpose, NOT WD-40). Ensure the cable moves freely.
4. Check the Return Spring: Ensure the return spring is intact and functioning properly.
5. Check for Vacuum Leaks: Inspect all vacuum lines for cracks, holes, or loose connections.
Important Safety Note: If the throttle is stuck, do not attempt to drive the vehicle. This is extremely dangerous. Have the vehicle towed to a qualified mechanic for repair. Trying to force the throttle open could cause further damage.
