Rough idle and excessive shaking of the engine could be due to a bad tank of gasoline, dirty fuel injectors, incorrect idle speed, exhaust restrictions, vacuum leaks, incorrectly installed or damaged spark plugs, a defective or clogged fuel pump or fuel filter, failing electrical components such as the ignition control module, plug wires, coils, and spark plugs, a defective airflow sensor,
dirty oxygen sensors and other causes.