Rough Gear Change at 40-60mph

I have recently noticed a rough transmission change at around 40-60mph in my 88 Camry (automatic transmission) with 163K. As some fellow users suggested in other threads, I tried easing up on gas when the transmission is rough, but doesn't help much. The ride becomes smooth, of course, after the car picks up speed again. Other than this the car runs incredibly smooth.

Any ideas what the problem might be? Would it be that it's time to change the transmission oil/filter? I don't know the last time it was changed, i got this car when it had 158 K. I have, however, changed the engine oil every 3000 miles.

It would be a good idea to service the trans as this is a maintence item anyway.It could be when it shifts into overdrive at this speed, in which case the fluid is probably not the culprit.Try turning the O/D off and see if that shift is still rough.

Also, another addition to what Joe has said...You probably should start changing the fluid at a certain interval also you should check the filter and clean the strainer, and this should eliminate the problem.