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Q: Car shakes, lights dim, won't accelerate

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My car is running terrible suddenly. Within the first 40 minutes of driving it, the car will start to roughly shake at red lights. The lights go dim, the idle drops significantly, it sputters to the point that it's got everyones attention around me and seems like it will surely die. I had to put it in neutral, one foot on the brake and other on the gas to give it some help to stay running. If it decides to do this (what I mentioned above) while driving down the road, it starts to sputter as it does, when i try to keep it from dying by pressing the gas a little harder nothing happens. It will not speed up, it actually slows down like the gas pedal isnt being pressed at all. It will eventually recover but it revives itself like its choking back to life. There arent any gas smells, although sometimes the heat smells faintly like mold when the car is warming up. My husband has replaced a few thing, includong the mass airflow sensor but nothing has worked. Any ideas are appreciated.

My car has 184000 miles.
My car has an automatic transmission.

Shaking or vibrating may be caused by many different things such as faulty spark plugs, poor fuel pressure or misfires. Other things such as a faulty idle air control valve may cause the engine idle to drop below the normal idling RPM which may also cause the motor to shake or vibrate more than normal. This creates a loss of power that resonates throughout the motor additionally causing other problems with ignition and fuel timing. Anytime a misfire is caused, this causes an imbalance in the motor which will cause the motor to shake or vibrate. The other issue that may cause this type of shaking or vibration is a broken engine mount. Engine mounts are generally rubber mounted braces that hold the engine in place to the chassis of the car. When these break or become weak or faulty, this may cause the engine to vibrate heavily. Due to the many possible causes of this type of shaking or vibration, I would suggest having an expert from YourMechanic come to your location to diagnose and inspect your vehicle.

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