I have a 2006 yamaha yz250 that I bought new. About 6 months ago I started to notice the backend seemed to want to push to the right in loose soil when excellerating or braking and the bike tends to stand up when making right turns and slide when turning left. I had the suspension revalved by a local servicers who specializes in woods type riding shortly after purchasing and everything seemed fine. Since I noticed the problem I have changed oil and seals in forks and changed oil in shock. I also have regreased linkage bearings and still notice the problem. Any suggestions what I can look at next. I have asked around and no one seems to know what to think.