1995 contour transmission jerks

I have a 1995 Ford Contour SE with an ATX that has 140,000 miles. Since about 90,000 I have been experiencing an intermittent problem with the computer and transmission. Every so often the transmission will start shifting hard, it lunges(hard jerk) when it shifts in and between the forward gears. When I check the codes it brings up a transmission code and when I clear it it takes care of the problem for a few weeks to a few months until it pops back up. I was told that it might have been the main computer, so I replaced it, thinking that there was a glitch in the old one, but even with the new computer the problem still occurs. Is there a sensor or chip or anything in the transmission that could cause this random code to be sent? Any help would be appreciated. Thanks!

when was the last time the trans fluid has been flushed?

when was the last time the trans fluid has been flushed?


Probably 100,000 miles...Sweet 96'

Probably 100,000 miles...Sweet 96'

It happened before and after the change, just not as frequently