TCC question

[87gninpa]

I know i am having problem with my TCC and am going to perplace it tomorrow, however i have a general tourque convertor lockup question. Since i hav begun having problems with my TCC i have repeadtedyl done the foot on brake for a half second test too see if the convertor is locked and the rpms go up. After about 40-45mph the convertor lock(i can feel it) and all the way up to about 50-55mph the test works. However anything above 60mph, the rpm do not rise? It my convertor unlocking when i reach 60? Is thi supposed to happen? Could this be why i am getting horrible gas mileage? Someone plesae help so i know how my car is supposed to act
thank you
shawn

 

[MeanBuicks]

You should always see that slight rise in rpm when touching the brake. Sounds like you may have a weak clutch that is slipping at higher speeds.