Auto trans will downshift sometimes all the way while at freeway speeds

What is your question?

Cycling on/off brings it back quickly. Feels like computer, not valve body. When this happens it brings up the check engine light and it won't shift right for days. Then every thing is fine for a while but not long. Is this my engine CP running amuck? You never know what or what starts it, but switched off to on brings it back to default and runs poorly.