I changed the filter and fluid a fair while back now so i dont think that may be it.
Only possible explanation that i can think of would be the old cooler was blocked and flowed slow, allowing the trany to reach some heat point with which it jerked.
Now with near new V6 Magna cooler it gets cooled down and allows the trany to operate at designed manner.
But then again i could be wrong so anyone with similar experience is more than welcome to add in