1996 Ford Ranger + transmission

1996 Ford Ranger + transmission

I have a 1996 Ford Ranger, with an automatic transmission. It runs like a champ but after the truck warms up, intermittantly, the transmission will not engage immediately. I inherited this truck from my now deceased father and while my brothers advise me to get rid of it fast, I would like to keep it, if it wont cost me too much. If the transmission doesnt grab right away, the time period before it does could be around 30 seconds and then it is fine. If I drop the tranny into D2, it takes right off and then I shift into D and it runs perfectly okay. Should I sell it before the tranny crashes or could this be a simple fix? thanks so much. Diana