well, I am also facing with the same problem but I WON"T GIVE UP....I have made some dreamy *and flowery plans for next 27 days...Go through the TIME VA material ( V02 ) and then take each type of questions generally asked in VA/EU and deovte 2-3 days to those types of questions ...take as many sectional test...just expose yourself to all kinds of questions that may be asked in CAT...The types would normally fall into :
-- Fill in the blanks
-- Parajumbles
-- Sentence Correction
-- INappropriate Usage of ONE WORD ( the most difficult one )
-- Matching Dictionary meaning ( forget it..they are not gonna ask this )
-- Missing word in a para...
The whole idea is to focus on each type of question at one sitting and become a master of it ( to your standard , of course

)...and then take on another type...
Might just help...who knows...
and as far as consulting grammar books is concerned...keep on doing it as and when you feel like...don't drown yourself into rules at this stage...