Help with tib shifting into 2nd issue

[Masonx]

I have a 2005 4cly tib and after the car gets warmed up like after about 15mins of drivng it will attemp to go into 2nd gear and the car will jerk really hard and wont shift untill you let off and just barely give it gas. I thought it was the tranny so we replaced that with a good one and that was not it, so someone told me it was the heat sensor and I thought that made sense since it only did it after it warmed up so I replaced that but thats wasent it and it is still doing it.
Any ideas

Thanks