If your vehicle is showing rough, shaking, or sputtering idle, here are the most likely causes and the parts you'll need to fix each one.
Worn spark plugs or failing ignition coils cause incomplete combustion in the cylinders. This results in engine misfires, leading to a sputtering and shaking sensation at idle.
A cracked PCV hose or leaking intake manifold gasket allows unmetered air to enter the engine. This creates a lean air-fuel mixture that causes the engine to idle roughly or surge.
Carbon buildup in the throttle body or a sticking Idle Air Control valve restricts the precise amount of airflow needed to maintain a smooth idle, causing the RPMs to dip and the engine to shudder.
If the engine RPM is steady but the vehicle physically vibrates or shakes heavily while stopped in gear, the rubber mounts that isolate engine vibrations have likely collapsed or torn.
A dirty MAF sensor incorrectly measures the incoming air, causing the engine computer to inject the wrong amount of fuel. This imbalance often leads to a rough, stumbling idle.
If the EGR valve gets stuck open due to carbon buildup, it continuously dumps exhaust gases into the intake at idle. This chokes the engine of oxygen, causing it to sputter or stall.
Clogged fuel injectors or a failing fuel pressure regulator can starve the engine of fuel at low RPMs, causing a lean misfire and a sputtering idle.
A burnt exhaust valve or blown head gasket causes a permanent loss of compression in one or more cylinders. This results in a constant, rhythmic misfire and heavy shaking that does not go away.