Don't go for speed too soon - try it slowly, however slowly you need to go to bring the notes out at an even volume. And I'd discourage using distortion until you can do it clean - no matter what the technique, you should avoid relying on distortion. But as Benoit said, perhaps try going over your pull-offs; once you've got the dynamics nailed, the speed and reticulation comes as easily as falling off a log. :)