[bunker1975]

I have a possessed Accent. Lately my car has been dropping out of 4th gear while driving on the highway. This does not happen all the time. I don't drive the car on weekends normally as I only use it to commute to work. I can usually drive to work the first day no issue, second day I may or may not have issues, by Wednesday I start having the issue on the way home and by Thurday/Friday it happens on the way to work and way home. When this does happen it will not shift back into fourth and when you come to a stop the engine seems to be accelerating from 2nd not first. Turning the engine on and off can reset everything but it usually happens again.
I do have a CEL for a rear O2 sensor but other then that nothing else has shown up. I had it into the dealership and it didn't act up. I had it to Mr. Transmisison and it wouldn't act up. I had the Tranny serviced and the problem is still there.
I have had it suggested to me, and reading forums it makes some sense, that it may be the TPS.
Anyone have a similar problem or heard of the same problem that may have a suggestion where to start?
Thanks

 

[sbr711]

Drop the pan, see if you find rollers and bits of TORRINGTON style roller bearing in the bottom of the pan..

What fluid was put back in the trans during the service... Hyundai - Kia SP-III --> you're ok..... Anything else, OOOOOps......

 

[bunker1975]

SP III was used but the issue was there before I had the fluid replaced.
The pan was checked when the service was done and there was nothing found.

 

[rsquared]

Did the shops test drive the car, and scan the ECM & TCM?

The TPS could be your problem, because the TCM receives a signal from the TPS. If you have a multimeter you can test the TPS.