GMAT Strategy

Hi I need some advice; I am frustrated with GMAT a bit right now. I have already taken it 3 times and have not achieved my desired score (730+). Actually I should rephrase that. My target is to get in to at least one school listed here with joint degree in policy/education so that I can work with small and medium size entrepreneurs in South and South-East Asia and Latin America

My background:
BS Mechanical Engg (India-State School) - 3.3/4.0
Started my own engineering design business while managing family engineering business for a year and had to close my business in a year

MS in Aerospace Engg (University of Texas ) 3. 18/4.0 Dean's fellow, Research assistant and Teaching Assistant - Took graduate level advanced math and economics classes with As in all of 4 of them
I am working with a large engineering firm as a design engineer for 3 and half years in US. I am managing 3 engineers in India and 3 in US.
Member of a local charter school governing council

Target schools - Stanford GSB, UC- Berkeley - Haas, Booth, and MIT Sloan.

1st attempt - October 2009
650(Q46 V34)
Studied for a week, took the GMAT and got burned. I realized that I needed to prepare more.

2nd attempt - November 2011
600 (Q47 V26)
Studied for 2 months, finished OG my practice test scores were above my target scores. Not sure what went wrong. I am not a bad test taker. I don't get nervous. I told myself it was just a bad day. I decided to wait for the next admission cycle and take the GMAT.

3rd attempt - June 2012
610 (Q41 V34)

This time I studied every single problem I could find.

Verbal
Manhattan GMAT SC guide
Power score CR Bible

Quant
Mostly internet forums
Kaplan math book

Questions
OG12
Verbal Review 2
GMAT Prep Question Pack 1

My practice test scores are
GMAT Prep T1 650 (Q47, V34)
MGMAT CAT 690(Q47 V37)
MGMAT CAT 700 (Q43 V42)
MGMAT CAT 710 (Q43 V44)
MGMAT CAT 660 (Q43 V36)
MGMAT CAT 660 (Q43 V36)

At this point I freaked out about my quant scores. I am an engineer I can do much better than this. So I studied quant for 2 weeks.

GMAT Prep T2 740 (Q48 V44)
GMAT Prep Reset T1 750 (Q49 V42)
GMAT Prep Reset T2 740 (Q48 V44)

After this I score 610 on real test. I am just clueless about what went wrong. I am a good test taker. I am very calm and confident. I am very rational so I am still calm after all these bad scores. I just want to figure out what is going wrong here because there has to be a way out of this.
I am thinking about retake in a month or so. Please any good strategy to get to my target score 730+

You have gone over a lot of stuff, more books is not the answer. Make sure you can get all of the questions you have already done correct. If not, then there are gaps in your knowledge. Study those questions more...

Thanks Jim, I am willing to give it one more try and that would be the end of it. I am going over all the questions I have gotten wrong so far and taking GMAT again in a month or so