I'm having this strange issue with my truck where at certain rpms and temps (ambient and trans) it shifts very hard into 3rd gear. If I take it real slow, it doesn't shift too bad. Also when the truck is still cold, it shifts normal. 1-2 shifts fine, just feel a slight disturbance when they shift, but 2-3 make the whole interior shake, it is very unpleasant. 3-4 is like butter, the only reason I can even tell it shifts is because the rpms drop. 4th-TC lockup is also pretty smooth. So with all that being said, does anyone have an idea as to what the issue may be?