93' Infiniti J30 won't shift to 3rd gear.?

[Stephanie]

I have a 93' Infiniti J30, I have replaced transmission, alternator, mass air flow sensor, throttle sensor, and fuel pump. It runs perfect but won't shift to 3rd gear. What could be wrong? Ever since it was given to me I always have to turn around and fix it.

 

[SPORTS CAR FIEND !!!!!!!!]

Its 17 years old and telling you it needs to be sent to the junk yard