Kickdown ???

Hi, everybody.
I found out the following on my 4.2r acquired only 1 week ago.
No matter what speed I give full throttle ( Kickdown ) it only accelerates quite moderately.
Turn it off, it's silky soft.
If I switch it down manually, he's gonna have a lot of steam.
It was supposed to be that way with the kickdown, right?
Can it be that my kichdown does not function ???
If so, how can I handle this? ( I've already stretched gas train around 2 grooves!

Would be very grateful for your help.

V8 Greetings sends Klaus