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Q: Low RPM/ Won't Shift

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I noticed that the car was revving very high (3500 RPM at 75 MPH). After letting off the gas and slowing down the car would not get out of third gear. It would get to 3rd from a stop and then seem to "Peg Out" at 3000 RPM and 50 MPH. I made it home however upon checking the problem this morning it seems to have gotten worse. There is no check engine light on for me to find a code from. I took videos of my car this morning to help illustrate what the current situation is.

https://youtu.be/kQJDgh9oDAw

This is after first starting my car this morning before driving, Seems to be running fine in park.

https://youtu.be/IT5dmti0PTQ

This is after shifting into neutral and revving before driving. Still seems to run fine

https://youtu.be/lrJbXFRK-nc

This is roughly 3 minutes after beginning to drive. Came to a stop at a light and this is what happened after,

https://youtu.be/9KN-3OWAiGA

this is after I got home and revved in park/ neutral

My car has 225000 miles.
My car has an automatic transmission.

A: Hello and thank you for contacting YourMech...

Hello and thank you for contacting YourMechanic. It seems like the IAC (idle air control) valve is malfunctioning. Check the wiring to the IAC for any debris and any corrosion. If the wiring harness is in good shape, then I recommend replacing the IAC. The IAC starts out by making the engine rev up and down at idle only, then it becomes worse by revving the engine up during driving conditions. For a more exact diagnosis, I recommend having a certified technician, like one from YourMechanic, diagnose the abnormal RPMs and shifting problems in person so that this can be correctly repaired.

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