Buick/Olds: 2001 Alero-slight jerking (?) RPM flucuation, coil pack, alero

Question
Hello. I just got this car on friday and today I noticed a small, very slight jerking or sputtering I guess when I'm coasting at right around 2000 RPM. When I feel this, I can see the RPMS either jump down to about 1600 or up to about 2400. It is a tad bit worse going up a hill. But it's not really bad. Not horrible jerking, just enough to make me nervous. The check engine light is not on.  

Answer
Hi,
I believe it is the coil pack. Try starting there. They can see on the coil where it is misfiring. Once that is replaced, not more shuddering!! BTW, no codes were registering misfires.

...since they already have the coil pack off, may as well chuck in new plugs. I put in NGK Iridiums IX.