Transmission shift problem?

-92 dodge spirit 3.0 ltr shifts perfectly and then sometimes will downshift into 2nd while at 40mph or less. I have to pull off the road turn engine off and restart and then it is okay, at least most of the time. Also sitting at astop light sometimes the kind of kicks as if trying to find another gear and when I take off it is nce again in second gear and won't shift up or down.