GMAT Strategy

Hi need advice on this issue esp if Stacy could add her golden words.

I have been working on my verbal for some time now. My first official verbal score was 28. Quant was 45. This totalled to only 610 and I knew that only verbal could drive up the score.(I am a non native speaker)

Eversince (march 2009) I have been working on my verbal. I have covered Manhattan SC, QG 11, OG Verbal. Maintained an error log,re-looked at mistakes, almost everything that is required to bump up the verbal monster.
As a result, when I do SC individually, my accuracy is more than 80%. same is the case with CR and RC.Which to me, means that i have atleast got the hang of problems and the concepts. But when they are bundled together in the form of a full length test, I just stumble!
During full length test I am unable to identify what is the error being tested, get confused in CR choices. Thus overall for a FLT my scores still remain the same, even though individually in a bunch of 10 my accuracy is good.
I have no idea how to weed this issue. I want to translate the >80% accuracy to my tests also. Any help , tips,suggestions?