I feel your pain!
I worked through Rita Mulcahy's prep book first, and then used the Exam Simulator to test my preparation with a broader range of questions. I actually started out with a 79% on my first Simulator exam, but I've been frustrated as my scores have DROPPED with subsequent exams (down to 66% on my 3rd Simulator exam). It feels like the exams are getting more difficult (i.e., testing more heavily on knowing I/TT/O in minute detail), and I strongly prefer to understand knowledge than to memorize details.
I did come across some very encouraging information on the CAPM Exam Simulator website. Go to My Statistics and the Exam Feedback tab. This tab takes you to a table showing ranges of 1st Attempt CAPM Simulator Scores correlated with candidates' pass rates on the actual CAPM exam. It appears to say that 81% of people who correctly answered
50-60% of their 1st attempt simulator questions have passed the CAPM on their 1st attempt. The pass rates increase to 88% for the 60-70% bracket and 94% for the 70-80% bracket. They don't even LIST any higher brackets, which might imply that hardly anyone scores consistently in that range on the prep tests.
I do think I need to put a bit more effort into learning and remembering the ITTO, but these Statistics give me some comfort. It would appear that the simulator exams may be pushing us beyond the level of ITTO proficiency that PMI actually requires of a CAPM-level candidate. At least, that's what I'd like to believe!
I'm also taking my exam this week. Good luck to you!