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Q: Barely any power when I step on the gas pedal, any ideas?

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The other day my Check Engine Light came on. OBD reader said P0300 - Random Cylinder Misfire. I checked the boots, they look good, the wires look good, and changed out all the spark plugs today. Took my Xterra around the block and no Check Engine Light came on, but the engine shakes and I can not go past 15 mph. When I'm idle the Check Engine Light comes on. I see no leaks in the vacuum hoses either. What else could it be?
My car has an automatic transmission.

Hello. From the symptoms you describe it would appear that your vehicle is experiencing an issue that is putting it into some sort of limp mode.

Limp mode is activated when the computer detects an issue that could potentially damage the engine and limits the power output of the engine to prevent serious damage from occurring.
A few other things I would check are the fuel and air filters, the ignition coils, the mass airflow sensor, and the transmission fluid level. I would also re-scan the computer to see if there are any other trouble codes that showed up after the spark plugs were changed. If you would like this all checked for you, a technician from YourMechanic can come to your car’s location to diagnose your car’s loss or power and make any necessary repairs.

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