95 Firebird Formula automatic tranny problems??

okay so here's the deal. about a month ago i bought this car (95 Firebird) from a private party. Drove the car around and it worked great. Last night I took the car to P.I.R. (Portland International Raceway) to see what the car could run on the quarter mile. The first four races the car ran great. On the fifth race I started accelerating and when the car reached the shifting point from 1st to 2nd, it just sat on redline for about 1-1.5 seconds before shifting and again from 2nd to 3rd. I spoke with quite a few people and everyone is saying I should get the transmission rebuilt. The car still runs and drives fine even at speed, just not at full throttle. I was hoping someone could shed some light on this. Thanks

rebuild it its a 95 probaly with a couple of miles on it so the only sure way is rebuilding it, my advice invest a little bit more but make a good tranny, put a super servo, a shift kit, a pressure valve on the pump and a good oil cooler