* Throttle Cable/Electronic Throttle Control (ETC) System: A sticking or malfunctioning throttle cable (if equipped with a cable) or a problem within the electronic throttle control system (most modern Jeeps use ETC) is a prime suspect. This could be due to:
* Stuck throttle cable: Physical obstruction or damage preventing the cable from returning to the idle position.
* Faulty ETC sensor or actuator: A sensor providing incorrect information to the engine control unit (ECU) or a malfunctioning actuator that's not properly closing the throttle plate.
* Debris in the throttle body: Dirt, grime, or other debris can interfere with the throttle plate's movement.
* Vacuum Leaks: A vacuum leak can cause erratic engine behavior, including unintended acceleration. This is particularly important for systems that control idle speed.
* Transmission Issues: While less likely to be the sole cause of immediate acceleration *after* starting, a problem with the transmission's linkage or internal components could contribute, especially if it's combined with other issues like a sticking throttle.
* Engine Control Unit (ECU) Malfunction: A faulty ECU can lead to various unpredictable engine behaviors. This is a less likely primary cause but should be considered if other issues are ruled out.
* Cruise Control Malfunction: Though less likely to engage *immediately* after starting, a malfunctioning cruise control system could be inadvertently activated.
* Shift linkage (Automatic Transmission): If the shift linkage is improperly adjusted or damaged, the transmission might not be fully engaging in park, leading to unintended movement.
What to do:
* Do NOT drive the vehicle. This is a significant safety hazard.
* Have it towed to a qualified mechanic or Jeep dealership immediately. Attempting to diagnose and fix this yourself could be dangerous.
* Explain the problem clearly and completely to the mechanic, including the exact circumstances under which it accelerates.
Ignoring this problem could lead to an accident. Professional diagnosis and repair are crucial to ensure your safety and the safety of others.
