True fully I think you would waste your money on any transmission shift kit, in an effort to help with the slipping. Pretty much once it has started to slip, it goes pretty fast. Same as a clutch in a manual transmission. The heat destroys the friction disk and the surface it rest against. When you feel that shudder, especially under load, there is alot of heat built-up in a very small time. Thats the reason the fluid starts to get burnt and stink, that heat is also transfered to the fluid, but it is to much for it. The heat generated is just to much for the system to cool quickly, so the fluid burns, and when it does it coats the parts in a film that results in them sticking. It probably doesn't sound like much, but that slipping Torque Converter will kill the transmission very quickly. The mating surfaces go fast they have you other option, the heat warps and glazes the linings. Behind that is the transmission's oil pump, it picks up that same heat and and will eventually fail as well. My transmission started slipping while towing, first it was only on hills where you got on it. Then a little more slipping, till it would slip hills or not, if you accelerated to fast. I replaced it before it broke, but it wouldn't take another tow. Though it might have lived for a while without towing.