97 dodge ram 1500 4x4.. weird question about 3rd gear

I got a question for all my mechanic friends… I have a 97 dodge ram 1500 4x4 5.9 46re trans. It won’t go into 3rd gear unless I unplug the battery and plug it back in and it works smooth as butter for about 10 then won’t go into 3rd gear anymore. Any ideas?? I was thinking a Vss sensor?

I’m thinkin’ that unplugging the battery might be resetting the Tranny Control Module.
But I’m not a tranny guy. I’m just guessin’.