I have been working on sweeping for a while now and I can pretty much play standard 5 string sweep patterns at a reasonable speed. However I am finding that certain strings are ringing out when I play them, notably the G.

I'm fairly sure this is not due to my left hand, because I have practiced lifting my fingers correctly. I think it is to do with my right hand but I am not sure.

Can anyone give me advice?
An issue i find sometimes is that I'm hitting natural harmonics when transitioning from one string to another, especially at the 12 fret. maybe thats the case?
Here read this, it should help: http://www.guitarlearningtips.org/guitar-technique/sweep-picking-exercises/

I am talking about the mindset you have to have when playing sweep picking.

Hope it helps,