See we thought it was a fuel issue initially. Had all the plugs coils and injectors changed still experienced the same problem. Finally figured out it was doing the stuttering only under 2k rpm in any gear but as soon as it got over 2k it ran perfectly fine in any gear so we took it to a transmission shop. They said need a new transmission is needed. Changed it out and we took it home and we got halfway home and it started again. Took it back and they changed some sensors. Went to go get it and same thing happened. Issue is that it doesn’t do it until after you’ve driven it 10-13 miles from cold. Well yesterday when I was dropping it off at a different mechanic to get diagnosed I switched to manual to see if it was still the 2k rpm issue that we originally brought it in for and it is.

Sorry Kia optima 2020