HKetherYou wouldn't happen to own a AMD card?
I have the same issue as OP and I do have an AMD card. Are they prone to this?
From my experience AMD cards have this micro stutter problem. I get 300fps and sometimes it will just micro stutter for no reason at all. The only way to fix this is to restart your computer and even then it might not help.
Do you havea 7xxx series gpu?