Dubstep help with Vacuum Plugin

[Funkle]

I've got a decent "wobble"bass sound going at the moment with the vacuum plugin. Only problem is that the rate at which the wobble happens (being controlled by the rate control to the right of the mod wheel and arpeggio controls in Vacuum) is slightly off time. Or more precisely it slowly goes in and out of time. Any one have any experience using this feature to do something similar to what im doing? This is my first try at making dubstep. Any help or any other tips on how to get a good dubstep sound would be greatly appreciated.