* Transmission Issues: This is a very likely suspect. A worn torque converter, low transmission fluid, or internal transmission problems can cause shuddering or shaking when the car shifts from park or neutral to drive, particularly under load (acceleration). The age of the vehicle makes transmission wear a strong possibility.
* Engine Mounts: Worn or broken engine mounts allow excessive engine movement. This movement is especially noticeable when the engine is under stress (like during acceleration after a stop), leading to vibrations felt throughout the vehicle.
* Spark Plugs and/or Wires: Old or faulty spark plugs and ignition wires can cause misfires. Misfires lead to uneven combustion in the cylinders, causing the engine to shake. This is more likely to cause a shake while driving *at speed*, but can be exacerbated under load after a stop.
* Oxygen Sensor: A malfunctioning oxygen sensor can lead to an incorrect air/fuel mixture, resulting in rough running and shaking. While less likely to be the sole cause of shaking *only* after a stop, it could contribute.
* Throttle Position Sensor (TPS): A faulty TPS can provide incorrect information to the engine control module (ECM), leading to poor fuel delivery and rough running, potentially causing shaking, especially when transitioning from idle to acceleration.
* Mass Airflow Sensor (MAF): Similar to the TPS, a dirty or malfunctioning MAF sensor can provide inaccurate readings, leading to inconsistent fuel delivery.
Troubleshooting Steps (in order of likelihood):
1. Check the Transmission Fluid: Check the transmission fluid level and condition. Low, dirty, or burnt fluid is a major red flag. If low, add the correct type of fluid (consult your owner's manual), and if it's dirty or burnt, it likely needs a transmission service or even a rebuild.
2. Inspect Engine Mounts: Visually inspect the engine mounts for cracks, tears, or excessive movement. A mechanic can easily assess their condition.
3. Check Spark Plugs and Wires: Have a mechanic inspect the spark plugs and wires. They can check for wear, fouling, or cracks. Replacement is often inexpensive.
4. Diagnostic Scan: A scan tool can read the ECM codes. This will pinpoint any issues with the oxygen sensor, TPS, MAF sensor, or other components that the ECM is monitoring. This is crucial for effective diagnosis.
Important Note: A 1996 vehicle is old enough that several components could be failing simultaneously. What you're experiencing is likely a symptom of a combination of issues, rather than just one single problem. A qualified mechanic should diagnose the problem properly. Ignoring transmission issues can lead to costly repairs down the line.
