95 sunfire, transmission problem?

[01s]

I have a '95 sunfire with a 2.3 automatic.
I will be driving at a steady speed in overdrive and it will start jumping .5 rpm, feels like it wants to down shift. I can put it into 3rd gear and there is no problem. I have changed the torque converter solenoid and it is still doing it. Any one have this problem or know what I should try next? Or am I looking in the wrong place, could it be a vacuum problem?

Thanks!

[maxwedge]

A misfire under load in lock up can do this, this can be better determined by having it scanned with a trans capable scanner for trans codes and check for tcc slippage. If ok I would suspect a lean misfire or a plug/wire condition.

[matt09524]

If the jumping is kinda rythmic, then I would suspect a misfire but only if it did it all the time whether traveling or stopped. Otherwise, have codes read if you can.

[hotbug1776]

you should be able to get the codes read, but it may be a dealer thing. the 2.3L ATX is OBDII so autozone MIGHT be able to get you the ecm codes, but I'm not sure about the tranny codes.

[01s]

Only does it in overdrive, no problems in other gears or during idle. My dad has a scanner from snap-on that we are going to try this weekend, but he said if there are no lights coming on in the dash then it probably won't throw a code. So that is why I have not put it on the scanner yet. Thanks for your comments, hopefully we will figure it out this weekend! Any other suggestions are welcome.