V-6,3100 pulsating rev at start-up

My daughter has a '96 Grand Am with a V-6 engine. When she starts it it is
taking a bit longer and when it starts the engine rpm is pulsating (up &
down) for about 5 sec. and then returns to normal. You can then drive away
with no hesitation or mis-firing at all. Is this a simple thing, has anyone
else had this problem?
Thanks...Ed

i did when my engine needed a tune up