Hi, its my first time posting here. I have an issue with my 2007 Mazda3 2.3 AT hatcback, While dring on the freeway around 65-75 mph the gears would slip out from 5th to 3rd making the car jerk and high RPM, AT light turns on for a few seconds then turns back off while the gears go back to normal. Went to 3 different shops and told me to replace or rebuild the transmission. So I did. Now with a rebuilt transmission its still doing the same thing. Yall have any experience like this or know a way to solve the issue? AT light only turns on when it randomly downshifts then turns back off so the shops aint getting any codes.

 

It's most likely a faulty transmission control module (TCM) which is mounted to the top of the transmission and usually goes bad due to the heat transfer from the transmission. You can either get a new one or save money by getting your original one rebuilt.