* Transmission Problems: A malfunctioning transmission is a strong possibility. Specifically:
* Internal Transmission Failure: A problem within the transmission itself (e.g., worn parts, low fluid, internal leaks) can cause erratic behavior, including unintended acceleration. The shaking is also consistent with this.
* Shifting Problems: A sticking or malfunctioning shift linkage or solenoid could cause the transmission to stay engaged in a gear even when the accelerator isn't pressed.
* Throttle Control System Issues: This system controls how much fuel the engine gets. Problems here can lead to unintended acceleration.
* Throttle Position Sensor (TPS): A faulty TPS provides inaccurate information to the engine's computer, leading to erratic fuel delivery and possibly unintended acceleration.
* Throttle Body: A sticky or dirty throttle body can cause the throttle to remain slightly open, even when the accelerator pedal isn't pressed.
* Cruise Control Issues (if equipped): A malfunction in the cruise control system could be inadvertently activating, causing the unintended acceleration.
* Vacuum Leaks: A significant vacuum leak in the engine's intake system can cause erratic engine behavior, including unintended acceleration. This is less likely given the other symptoms but remains a possibility.
* Wiring Harness Problems: A short circuit or damaged wire in the engine's wiring harness could cause signals to be misinterpreted by the engine's computer, leading to a variety of problems including what you're experiencing.
What You Should NOT Do:
* Do not drive the vehicle. This is unsafe. The unintended acceleration could lead to an accident.
What You SHOULD Do:
* Have it towed to a qualified mechanic. Do not attempt to diagnose or repair this yourself unless you have extensive automotive experience. The problem could be dangerous.
* Mention all symptoms clearly to the mechanic: The information you provided is crucial for proper diagnosis. Include the details of when the problem started, and if any other unusual noises or behaviors were observed.
* Check your transmission fluid: If the level is low or the fluid is burnt, it strongly points toward a transmission issue. *However, do this with caution; an overheating transmission can be extremely hot.*
Ignoring this issue is dangerous. The sooner you get it professionally diagnosed and repaired, the better. The cost of repair will depend on the specific cause, but it's likely to be substantial if it involves transmission work.
