Rough Unstable Idle

The engine runs unevenly. If bad enough, the car may shake. The engine idle may hunt or fluctuate in rpm and may be bad enough to stall.

POSSIBLE CAUSE ACTION



AT OPERATING TEMPERATURE

Vacuum leak Check vacuum lines and routing
Check intake manifold
and vacuum components



Positive Crankcase Ventilation (PCV)
malfunction



Restricted exhaust Refer to Catalytic Converter