Im assuming you checked your fluid level to make sure it isnt low or burnt....
Honestly taking it to a good trans shop for diag would probably be a good idea to be safe...but yea...sounds like the trans may have issues. There are better options...like BTS, suncoast, ATS, etc....but i honestly dont know the prices. You might want to PM the user EricB, hes a pretty knolegable tranny guy and could probably steer you better than me