2000 Ford Ranger 4x4 had some issues with vehicle not starting unless in neutral now can not get vehicle into park

The vehicle slips in reverse from park on its own and I cannot tell which gear it's in.

I had a rebuilt transmission put in and it was fine for about 30,000. But now it only shifts during the summer. Then it gets cold and it wont shift into 3 or overdrive. Sometimes the overdrive lights flashes but not all the time. The overdrive button doesn't work. I let it run for 10 min every morning before i go to work or it wont shift at all I store it in my grage.