A904 issue with stock converter

Only thing that comes to my mind is I've had a similar "feelings" when a sprag was going away in my race cars. It felt like the brakes were applied to the point of wanting to lock up. Don't know if the kickdown adjustment or something else could be involved. Regardless of the problem, for more clues, drop the pan and look for debris and see if the rear tires rotate freely by hand when off the ground and in neutral. Disconnect the driveshaft just to be sure it's not something in the rear.