The car is jerking randonly. The mechanic change the transmission selenoid.
it was ok for 1 month. the problem came back again and he did the tune up
and the the problem continues. what could it be?
It is probably varnish buildup the passages and some of it is getting into the solenoids, try pulling out a quart of trans fluid and add a quart of TransX and see if that will help clean it up and start making it shift better, it will take some time to work as it has to get in the valve body before it can start to work so give a week of driving.