I have a 1995 ford ranger 4.0 and my transmission is slipping 2nd going into 3rd. Any idea what the problem is?

 

Welcome to the forum

You have a 4R55E automatic in a 1995 Ranger 4.0l

4R44E, 5R55E and 5R44E are all similar so what applies to one applies to all, alphabet soup, lol

Have a read here: Seven Common Problems With The Ford 4R55E Transmission

All automatic transmissions have many interdependent parts, so identifying why transmission slips between 2nd and 3rd is a GUESS at best
Slipping is very bad, it wears out the clutches and bands(brakes) inside, so just a heads up to not let it go on too long

Also Google: 4r55e 2-3 flare

"flaring" means slipping