99 3000gt cold transmission problem

i have a 99 3000gt automatic tranny, here is my problem whenever i put my car into reverse or drive when it is cold i have to rev up the engine for the car to move but after it warms up it works fine, is this normal for the 3000gts? or do i need some servicing

Definitely not normal. Check the fluid level. If thats fine then most likely the tranny is on its way out.