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Q: My car periodically starts with a high idle.

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My car will start with a high idle, about 2000+ RPMS and then subsequently lose power while driving. The car will sputter and not go above 50 miles per hour. This happens sporadically and I cannot determine what causes this or how to fix it.

My car has 95000 miles.
My car has an automatic transmission.

This is a common sign of a failing mass air flow sensor. The mass air flow sensor is a unit in the intake system that monitors air intake as it is mixed with fuel prior to being injected into the motor.

When this fails, this can cause an imbalanced air/fuel load to be supplied to the motor which often times results in the engine starving for air or fuel. This is what causes the hesitation or loss of power you describe. This can also cause the engine to struggle to idle for the same reason. This may also be related to a vacuum leak which will cause the car to idle high as you describe due to a lean fuel condition. At higher RPMs, a lean fuel condition will also cause a loss of power. I would suggest having a professional from YourMechanic come to your home to diagnose and replace this sensor.

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