2002 dodge ram 1500 trans problem

Things just wear out. Sometimes allot sooner than they should due to poor quality control where their made. Do you know what transmission is in it? If it's a 360 engine you have a A518. If you have the 4.7 litre you have a 45rfe. I don't know much about the 45rfe but I know the A518 has bands to adjust. If this is what you have make sure to properly adjust the bands when doing the fluid change. A worn rear band could be slipping causing your problem.