JKRIFX4

I'm having a shifting issue between 3rd and 4th gear, but only when the torque converter is locked in 3rd gear when it shifts. There is a pretty decent jolt when it does this. My question is... If I change when the torque converter locks in 3rd with my Edge tuner, which way should I tune it? I was thinking if I go up in mph when it locks it may not happen as often... Anyone have any advice? The transmission is not stock, it was upgraded by the previous owner, I'm not sure of the specifics though....