Ok I had my trans rebuilt about 2 years ago and have put about 3000miles on it. The car wasd down with a spun bearing for thoes 2 years, then I got the car back with the new motor. about 500 miles later the problem started happening, I would floor it in 1st gear and when rpm's were high(don't know how high the tach in slow but said above 5000RPM but I was probably at 6500) the car would usualy shift there and instead it would bounce off the revlimiter in a speraticly like the trans wanted to grab but couldn't. Then in secound it would once in a while do it at about the same rpm's, but never in third but i only tried it twice. Once when i was flooring it in secound it bounced off the liiter at about 5500rpm then kept accelerating then at about 6000 started bouncing like nuts. Back when i had the trans built it would bounce off the limiter when it was suppost to shift at5800rpm on the stock motor. The shop said it was some valve in the valve body and they said it had rounded itself out and they put a bigger valve in and the problem was fixed. Back before the trans was rebuilt in the first place the same proble was happening but shortly after it started happening the trans blew. The trans shop wont cover the trans because of the motor. I had all the electronics replaced when the trans was built. And it has a cooler on it now. The trans has never been beat to hell the most stress it has probably seen was the DYNO sessions. It seems to act up most when the trans is fully warmed up. It almost seems like the trans is letting go and just can't handle the power or something but i've herd it can, just not for a long time but with only 3000 miles on it and maby 500 more since the new motor(in sig.) I dont see it being burnt up yet and the original trans fluid is still in it and is not apear to be burnt and is full. I was thinking maby the valve body but I don't know much about transmitions. Anything would be helpfull thanks.

 

I can't remember but does it have a kick down cable on it? If it does it may be stuck in kickdown position. "wide open position"

 

Gearstar transmissions come with a 3 year warranty... If you call Zack over at Gearstar he may be able to help you diagnose the problem even though your not in the market for a new one. Hes a pretty cool guy,