Have you messed with any of the neddle setting since you broke it in? If so start from factory setting for the high speed needle and go from there. I was having the same problem last night. I screwed the HSN all the way in and then backed it off 1/4 of a turn till it would stay running. You will have to back it out aways. I know have it running last a rabbit on crack and going to mess with the LSN to get all the power out of it that it will do.