transmision masters in reynoldsburg will look at it for free... if you have the 1-2 but the 2-3 slips the trans is most likely bad, however it is all electronically controlled by solenoids and whatnot. you might also see if someone on here with autotap or hp tuners can look at it for you.
I cleaned up most of this thread but left rotarded's post. try to post normally in the tech forum we will answer your questions if we can.