Rough/Unstable Idle or Stalling

Definition: The engine runs unevenly at idle. If bad enough, the vehicle may shake. Also, the idle may vary in rpm. Either condition may be severe enough to cause stalling. Engine idles at incorrect speed.
POSSIBLE CAUSE ACTION
Throttle linkage sticking/binding Check and adjust throttle linkage and cable

Fuel metering Check air/fuel ratio (02 sensor voltage).
Perform injector balance test.
Check fuel pressure (check return hose).

Incorrect idle speed Check and clean throttle body.