Rough Idle

1. Hoses and Connections
2. Idle Air Control (IAC) Valve
3. Fuel Injector
4. Contaminated Fuel [1]
5. Manifold Absolute Pressure (MAP) Sensor
6. Exhaust Gas Recirculation (EGR) Valve
7. Engine Control (ECM) Module

NOTE: The system that could be the source of the symptom are listed and should be checked in order, starting with #1.

[1] Fuel with dirt, water, or a high percentage of alcohol is considered contaminated.