1996 z-28 tranmission problem?

I have a 1996 camaro z-28 with about 103,xxx miles that wont shift when pinned. The transmission shifts fine otherwise but I have to let off when I'm accelerating hard. If I don't let off it redlines. The transmission doesn't slip. I have read a few blogs and posts saying that 96 GM vehicles have a problem with their TPS, throttle position sensor. Some say this effects their transmission. Would this be my problem? Or is it something more serious?

well since the tps sends a signal to the ecm, and the ecm controls the shift points...it's possible.

just to note, at WOT the shift points will be high, but it shouldn't red-line.