Q: Car runs fine at first then will not accelerate past 20 mph on a 2003 Kia Rio

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If car sits over night then was to drive it in the morning it runs fine for 20-30 minutes then out of no where the car will not accelerate past 20 mph. You have to pull over let it sit for a few then go which runs fine but then out of no where will stop to accelerate past 20 mph. I had already brought it to auto zone to see if any codes come up and they told me that it was the speed sensor which I did change but was still having the same problem.
My car has an automatic transmission.

Hi there. The problem with the auto part store scanning is they do not complete the inspection to pinpoint the precise source of the issue. For example, if an error code might indicate an issue with the speed sensor, it’s not always the sensor that is the issue. In fact, in most cases, it’s the electrical harness or just the connection of the sensor to the harness that is the problem. Your best option to correctly have this diagnosed is to have a professional mobile mechanic complete a car is slow to accelerate inspection at your location.

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