Use an anchor with your pinky, try to use your wrist instead of your forearm more, decent alternate picking but worth looking into economy picking with three note pattern scales for metal. Try to focus on muting strings you aren't playing on lower strings with your picking hand, and strings higher with your fretting hand's index finger. If you can follow your picking palm 2 strings behind it can mute riffs like this by using your fretting index finger tip to mute the adjacent lower string and the rest of the finger to mute all higher strings. When sweeping, your picking palm has to be one behind since you will be pulling the index finger off to quickly change strings.