I'm sorry you're having a tough time with the test.
Re: your practice tests, did you take them under 100% official conditions? Essays, two 8-min breaks, holding yourself to official conditions as much as possible? Did you see any repeated questions - questions you'd seen before?
How's your timing? (Note: you can finish a section on time and still have timing problems.) How's the balance of timing between questions? Are you averaging about 1m15s on SC, 2m on CR, 2.5 to 3.5 minutes reading RC passages, 1m to 1.5m on questions? Are you not spending more than 30 seconds above those averages on any single question?
You can use this article to analyze your most recent MGMAT tests:
http://www.manhattangmat.com/blog/index ... ice-tests/Ah, okay, I just got to the part of your write-up where you mentioned timing. So on the last 8 questions, you had 11 minutes left, and most of those questions were of the longer variety. Yes, that's a significant timing problem and likely caused a fairly significant drop in your score. If you missed all 8 questions, that could have caused something like a 15 to 30 percentile point drop in your score!
The penalty for getting multiple Qs wrong in a row can be quite large. There are variables, such as how many of those Qs happened to be experimental questions.
So timing is definitely pulling you down. I do also want to know whether you've been taking your practice CATs under 100% official conditions, because it's possible that your practice test scores were artifiically inflated.
Go analyze your tests and then come back here and post again.