Sarah is right, you have a healthy amount of enthusiasm. Koodos. I can tell you what helped me, I am horrible at standardized test too. I'm actually diagnosed dyslexic, but I don't tell anyone so there is an unknown factor and only really is an issue under extreme stress.
Did you take an undergrad course in Logic? If not, try stopping the pre tests and getting an intro book to logic. A good and short starter book is Logic Made Easy by Bennett (I may have misspelled her name). Also, if you haven't already, try the power score series. Good luck and I hope you find a way to up your score.