hey guys....i just got a transmission fluid change.now when i m driving around 65 mph...and i press the gas steadily, the rpm would rise like 300 to 500 by itself.it seems like the car shifted to a lower gear but i dont think it have shifted...it only do that once in a while and only when its going uphill...and the rpm would rise and go back down for a few times before it stops....what would this be....do i need a tune up or somethings wrong with my trans...hope someone can help thanks

 

The car has a lock-up torque converter. When it engages there is no slipping. Under a load, like going up a hill, the torque converter will unlock. There will then be slipage between the input and out put of the torque converter, and the RPMs will rise.