I just had my transmission rebuilt. Failed with no symptoms leading to it. Anyway...I had the builder massage it a bit. They put a trans star triple disc TC in. They installed and transgo shift kit. Modified the present valve body, New billet shaft, as well as, new everything else. I really could not tell to much that any performance parts had been added. It does not downshift as easily as it used to. At 70mph I could stand on the accelerator and it would go into passing gear. Now it just lugs. It will downshift at 60, with no problems. Does he have the throttle cable out of ajustment? I have a 3 year / 100,000 warranty.

 

You should ask him.

But, I say since it is at 2,000 rpm at 70 or so, why downshift it? It is at the torque peak so use it!

 

sounds like throttle valve cable, esp if its not shifting at the right points. A little tinkering with it should get you where you want to be. I haven't done it enough to do my own....