Automatic Transmission Control Module problems of the 2004 Kia Motor Sedona

Took vehicle to dealer at least 15 times, they said not kicking up any era codes. The throttle body was changed also transmission control module (tcm ) was then changed. This did not fix the problem. They did something with the grounds. In February 2005 they put in a new transmission. Like the car it was losing power, and car was gearing down on its own. At first this only happened once or twice a week, but currently it happened every time consumer got into the car. The last this happened consumer pulled out onto a road and car had no power, and did not want to accelerate. It was almost hit by a tractor trailer. Drove to dealership did not turn off the car. Technician drove the car, and he said that the transmission kicked itself into safe mode, which meant the car stayed in second gear while driving.