Hi Shadriss,
I think I am having the same problem. I hope you can help me.
Just finished installing STEP and everything is perfect except whenever I go indoors clutter starts flying around (I'm even taking damage from getting hit in the head with pots lol)
Even when I can't see things flying around there is a constant noise of clutter smashing around when ever I go inside somewhere.
Other advice said I needed to change the skyrimprefs.ini and change iVsyncPresentInterval to =1 or add it if it wasnt there. I had to add it.
It didn't seem to do anything at all.
Yours says 'iPresentInterval=1' which I found is already set to 1 in my ini.