Hi Lotus Sutra,
It is evident from your score that you are good at the Quant. You must make sure that in the process of improving your verbal, you do not loose focus of Quant. I will suggest you device a 80-20 or 90-10 plan for verbal & quant. By this I mean study verbal for 80% of the time and Quant for 20% of the time or something similar as per your comfort levels.
Coming to verbal, I would suggest you go through the strategies first for each of the section. I had followed MGMAT for SC, Princeton Review for CR and I was definitely helped. You may want to refer them but if you already have other standard material and you feel they are good then continue with what you have. For RC, I feel it needs more of a reading and comprehension practice than working on the strategies. Best way to improve RC is by reading articles, editorials etc.
1: Start solving problems in timed conditions once you feel you have understood the strategies and you have improved your accuracy. Right now you should concentrate on improving the accuracy. Once that is achieved then attack the timing. You can make a plan in such a way that you work on your accuracy till 1 month before main exam (worst case 3 weeks) and then last 1 month/3 weeks you should time your questions.
2: Try solving 2 or all 3 verbal section questions everyday. Do not solve only CR on one day, only SC on another. Atleast a mix of 2 sections is always a good idea.
3: Keep checking your strong and weak areas and devote more time to the weaker sections.
4: Since your problem is stamina, I would suggest you take practice tests at regular intervals. Also, you must take full 4 hour exams with AWA. You can also make your own tests by taking questions from each section from any source and solving them in a timed environment. Since you are good in Quant, you can atleast make a 41 question test of verbal and solve it in 75 mins. This way you will not have to find a 4 hour slot and you will also practice solving questions in timed environment.
Hope this helps. Let me know if you need any specific information.
Regards,
Sandeep