Rough Or Unstable Idle

Check intake air temperature sensor.
Check purge control solenoid valve (if applicable).
Check vehicle speed sensor.
Check engine coolant temperature sensor.
Check barometric pressure sensor.
Check ignition switch.
Check idle position switch.
Check throttle position sensor.
Check TDC sensor.
Check crank angle sensor.
Check power steering oil pressure switch.
Check A/C switch and power relay (if applicable).
Check inhibitor switch.
Check oxygen sensor.
Check airflow sensor.
Check motor position sensor (if equipped).
Check fuel pressure.
Check for disconnected or damaged vacuum hoses.
Check PFI system malfunction.
Check for stepper motor malfunction (if applicable).
Check for fuel injector malfunction.
Check for power transistor malfunction.
Check for vehicle speed switch malfunction.
Check for ECU malfunction.
Ensure electrical harness, connectors and wires are not broken or loose.