Welcome to the Q&A Forum

Sounds to me like you're seeing these rankings, then you're trying to 'tweak/optimize' these same pages to go higher in the ranking and so those 2-3 weeks are w/ index A and then your new 'tweaked' page  Index A version 2.0  gets indexed and throws you into a new ranking/tailspin

Will do!   I love the value i get from SEOmoz, and this sounds as if this is the one thing i'm missing.  I'll report back soon,  Thanks for the recommendation