Transmission stutter/rev

Chrisy

2010 Z (automatic/paddle shifter)
I have owned my car a few years and just had the transmission fluid changed because it had started to pause/stutter a bit from 1 into 2nd. I thought at 80,000 miles perhaps it needed a flush and didn't know when it had been done last. Now it seems to be pausing both bringing up speed and slowing down, even without breaking. It also is jumping RPM from 1.5 to 3 and sticking/revving instead of making a smooth transition back down.
I brought it back to my mechanic with my concerns last week and he cleared the computer in case that was the issue. But it seems even worse.
If anyone has recommendations or experience, I'd appreciate your comments. Thanks!
~Christina