I've been working on more technical songs lately. I'm working on composure and barbarian by August Burns Red. For the most part I'm able to keep it clean, but I still hear a little string noise (clean channel) when I do my pull offs for the main riff. does anyone have tips for improving my muting.

I'm also working on sweeping, string skipping, and alternate picking. Any muting tips for those would be helpful as well.
you're just gonna have to work on it like everyone else, go slowly and keep your thumb in the middle of the fret board.
Why should I come down?
From here, I can see forever.
I agree 100% with RocknRollRay

Its not about doing it quickly, if you can, video tape your left hand, and find what your doing wrong, you may be pulling off too hard.

As far as the other stuff goes, you have to do it without mutting before you can do it with mutting, this will make your pick hand work harder!
most guitarist push way harder than they need to, relax and give it time. use a metronome and have fun

Crawl through knives.