Damn This Sweep Picking! Is It Really That Hard?

I've been working on sweep picking for about a year now. I actually got started with it when I first discovered Masterclass. I can sweep major and minor patterns and other variations of the such with 16th notes at about 130 BPM cleanly (and that's only on a really good day) anything faster than that is tripping my left hand up like its got the downs syndrome or something... I practice moderately. Sometimes sitting down for about three hours or more.. sometimes two, and sometimes I won't get to practice for a day or two because of my demanding schedule with a band and going to school... Anyway...

I need to get faster at sweeping to pull of some impressive soloing in the new material my band is writing. I need to get to 160 BPM or better. I know practice practice practice but when I try to do it faster my fingers just won't have it, and so I feel like I really can't practice sweeping and faster because it sounds horrible and I may be developing bad technique habit in doing so...

Aside from rigorous practicing, can anyone offer advice on how to get faster at this sweep picking arpeggio maddness mayhem destruction balls to the wall?

Also, check out my band: Myspace.com/ourmalignantbeloved