I have a problem where if I'm in 1st person view, moving the mouse to look around causes a horrible stuttering effect. If I simply move or strafe and stop moving the mouse when it gets jittery, it's perfectly fluid.

I've got a good system and generally get FPS hovering at 60 everywhere, so it's not that. I have tried what I could already find through searching. Mouse optimization in the ini file did nothing. Adding cell buffers to the ini file helped a little, very little. Adjusting mouse sensitivity in the ini files and my mouse driver had no effect. Disabling v-sync in in the ini file had no effect. The only thing that stops the problem is the mod "Skyrim antilag". It uses what I'm guessing is a modded d3d9.dll file. First I can't use the FXAA injector with the antilag no mod. Not a big deal, I'd rather it play correctly than look a little nicer for now. Second, I can't get v-sync to work at all either through CCC, D3Doverrider or DXTory so I get awful screen tearing which is almost as bad as the mouse stutters.

What am I missing?

I had the same issues and managed to fix it by using a FPS limiter. I personally use the one that comes with ENB (see here http://enbdev.com/download_en.htm). I still have the older version 1.02 so I haven't tested this latest one.

Do you have Ambient Occlusion enabled? I have the exact problem you are describing if I turn AO on. I have tried everything and finally gave up and am now playing with it turned off.