changed and when? Auto trans need good clean fluid often. Mild rpm increase probably a sign of internal slipping. If a really high mileage car and tranny not serviced not good. What color is the tranny fluid on the dip stick? Should look reddish like new fluid. Place some of the fluid on a clean piece of white paper and let the blob sit flat for a while.
Report the color especially at the outer circular edge as it spreads out before doing a fluid change.
If you do a change just do a gravity drain not a flush. Need to use the correct fluid per the owner manual no other.