I have a 91 camaro 350 700R4 i just installed a transgo shift kit 3rd was working after transgo install but i didnt like shift points so i took it back out and converted it to manual shifted auto so it is now FULL MANUAL. Under normal throttle it takes off and shifts into 2nd perfect then when i shift it into 3rd it does nothing at all no noises or anything but then i put shifter in 4th and it upshifts into 4th. If you have the shifter in 3rd gear its just like its in 2nd but if you give it over 2/3 throttle i will upshift into 3rd but as soon as you let off the throttle in 3rd it will instantly shift backdown into 2nd no matter what the rpm's are with out moving shifter from 3rd position.

 

Come on guys. Not even any hints or anything.