Auto trans Kick down?

[JoesAu]

What controls the kickdown in the Auto?
reason i ask is because lately my car is'nt kicking back gears from about 80km i put my foot right down and it doesnt kick back hard to 2nd! or 1st, stays in like 3rd then winds right out to 150km's+,9/10 times it wont kick back from 80km's its almost like i have to hit it at the right time or it wont kick back and work hard, overtaking is a pain!!

Foot right down at about 60km's and it kicks back hard, im wondering could there be something wrong with the throttle cable? it all looks tight no loose cable, ive replaced the TPS as well. Its starting bug me any got any suggestions?