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Q: Hesitation when accelerating.

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When the car is cold it runs great just a slight hesitation when accelorating about 3,000rpm's. After the car warms up it is a mess. The motor starts moving up and down with the rpms when at a stop light or even while driving. It sounds like a misfire, i checked everything i could think of, plugs, wires, cap and rotor. I even replaced the fuel filter. The problem started after i replaced my last spark plug( i changed the other 5 at an earlier date). When i felt the misfire and the cel blinking i replaced the 6th one. I went to get gas after i completed the job, and thats when i noticed something wrong. I thought bad gas possibly. But after emptying the tank and refilling the tank plus some gas cleaner its still persisting. I decided to check the air filter. Any kind of constriction can be caused by a clogged filter. I found oil on the lower end of the airfilter. I don't know how the oil got in the airbox but its a little bit and it seems as its coming from the throttle body.

My car has 188000 miles.
My car has an automatic transmission.

You may have spark plug wires that are damaged or the plug you put in got damaged while putting it in the hole. If you accidentally closed the plug gap then the plug will cause a misfire. I recommend removing and checking the plug and wire first. If they are faulty, you may need to have the spark plugs replaced. I recommend having a technician, such as one from YourMechanic, diagnose your car’s hesitation issue in person. This way, you can ensure that you are getting the correct repair.

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