How much do you find it lowering and raising? What are your main keywords? Usually there's a "Google Dance" that takes place whenever you're running marketing campaigns. What kind of backlinks are you pushing to your site? If you're worried about getting sandboxed chances are you're pushing the wrong kind. Are you currently autoblogging, your spin seems to be fairly good, 30-40% unique w/ editing at all? - Noticed some similarities to Phone Arena.
If you're in the sandbox you would not be dancing, you would be nowhere, point. There was recently a google algorithm update, it could be that, just adjusting... or, as highlighted by Bruce-Wayne, you could be running the wrong kind of campaign...
i agree with imatheweb , it is google dance keep building quality links and you will come up even stronger.