Causes of Car Engine Vibration While Driving and Stopping* : *Primary Causes of Engine Vibration:* 1. *Spark Plug Damage*: Worn out or fouled spark plugs Improper gap spacing Spark 7 Symptoms of a Bad or Worn Spark Plug If your car is not running smoothly, a worn spark plug could be the reason. 1 Hard Starting When the spark plug is Engine Shaking Diagnoses Japanese Auto Repair Why Is Your Car Shaking and Vibrating? Changed Spark Plugs And Coils Still Misfiring Heres the Real Fix do spark plugs make a difference in acceleration? if they look like this vs new, don't want to replace this if it doesn't need to be : r MechanicAdvice