I had that trans. in my 95 V8 Dakota & had similar problems & wouldn't shift out of 2nd gear until about 3600 RPM when it was not warmed up. There were no major leaks but, I added a bottle (8oz.) ATP brand AT-205 Re-seal & within 20 miles it was working great. It even chirped 2nd gear when I got on it. Try it & check your T.V. cable & make sure it is adjusted properly. Being out of adjustment will cause problems. Carefully remove the cable from the throttle body linkage, make sure throttle is at full rest position & make adjustment so the cable lines up with the ball on the linkage with no push or pull on the T.V. cable. Done.
