Tuning Anyone Work on Anschutz Rifles?

I think the stabilizer on my 9015 HP is giving me problems. I'm getting spreads of 20+ fps on 20 shot strings. It will hold steady, at say 710 for about 5 shots than drop to 696 and give me a flier. Then it will return to the 710 range for another 5-6 shots and do the same thing. No consistency and the S.D. runs from 5.2 to 6.4 between strings. Seems I should be getting a better ES and S.D. from an Anschutz.

Any help would be appreciated.