1995 Dakota trans problem A500 98k

When cold the trans works fine for about 15 mins, then its like you put it in nuetral. No forward no reverse. A friend suggested changing filter/fluids so I did. Worked great for about 4 hrs then same thing. Leave it sit for a few hours and it works good for about 15 mins then nothing. Should I try another filter or something else?

Here is my “go to” fix for automatic transmissions before I rebuild or replace them. Just add a can of Berryman B-12 Chemtool to your transmission fluid. It works because I have used this product for about 20 years and can personally attest to it’s performance.