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

Maybe a dumb question, but have you checked the fluid level?

Yes, the filter was changed and the tranny was completely drained, with new gaskets, new fluid etc. I thought that this might be the problem but no joy, it didnt fix it. Further thoughts? Thanks

When was the fluid changed, after the problem was noticed? Was the correct fluid used. How was the fluid that came out, dark and burnt-smelling or red and O.K.? Way too often the wrong fluid is used in transmissions and that can kill them.

D2 starts it out in second so it seems like the problem is in 1st.

The fluid was dark but no distinct scent, the color appeared to be okay, the mechanic was fully certified as a master mechanic, ase certified, so on. He seemed to think that this was peculiar to the Ford Ranger series.

Does anyone have response to my original question? Anyone? Thanks.