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Q: Idling very rough after I bought the vehicle.

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Just bought today so I don't know much, but it barely idles at all. Sounds horrible, has a ring of dark soot around tail pipe, but only 120,000 miles on a v-8 and looks almost brand new with little things like all the fluids being fresh and full, so I figure it must not have been abused. What can I say, it was immaculate, and I bought it really cheap.

My car has 120000 miles.
My car has an automatic transmission.

A: Hi there. First check for any vacuum leaks...

Hi there. First check for any vacuum leaks. A small vacuum leak will cause the engine to raise up in throttle, but a large vacuum leak will cause an engine to stumble. Check the fuel injectors and see if they are leaking. You can unplug one injector at a time with the engine running. When an injector is unplugged and the idle begins to smooth out, then that injector was leaking or not spraying correctly. Check the mass air flow sensor (MAF) and see if its dirty or oily. If the MAF is dirty, I recommend replacing it. You can clean the MAF with a can of electrical cleaner. Last, check the conditions of the spark plugs and make sure that they are sparking. If the spark plugs have burn spots on them, replace the plugs, but also check the fuel system for a stuck injector. If you need further assistance with your engine running rough, then seek out a professional, such as one from Your Mechanic, to help you.

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