Trans issue or something else?

Put the car in neutral on a flat road and give it a push.
Assuming the tires have the proper pressurize, it should start to roll with light/moderate force fairly easy and stop after a couple of feet.

Put the car in Drive and let off the brakes. It should start to roll quickly and roll with a swift walking pace (depending a bit on idle speed).

You could also try and feel for any noticable hot(ter) brakes after a short trip around the block.