Rough idle could be due to
a bad tank of gasoline, dirty fuel injectors, incorrect idle speed, incorrect...
The poor operation that you are describing 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...
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.