You have to make sure that you're actually GETTING something out of what you are doing. I can only imagine trying to take a giant test like this with the demanding schedule of a surgery resident. If you are not a US grad, have been long out of school, those factors would not help either.
My basic advice:
1) don't overthink questions. In a lot of situations the simplest answer really is the best. ( Got an elderly woman who has lost 15 lbs in her nursing home? MAKE SURE SHE IS *TRYING* TO EAT FIRST before going all Pan-CT on her.)
2) identify the questions that 85% of people are getting right, that you are not. The breakdown would be the first place I'd look. I'm also wondering about the questions that studying doesn't really help--the "common doctor sense" ones the FIP section focuses on, like above.
3) as you study, ask yourself what the most concerning findings are for a given disease process (suggesting good outcome or bad). The ACM section is riddled with this stuff. (orthopnea, for example, is BAD NEWS for CHF).
4) DO the NBME practice form on the NBME self-assessment website. Pay the 60 bucks, work through it. It gives you the items you got wrong after you're done. Then go look all of those up and DO IT AGAIN.
5) If you've failed twice doing all the subject tests for step 2 on the same website might not be a bad idea either. I reason that the NBME is the best source of info for their own exam. I felt like those forms are a bit harder than what you have to face.
6. I don't see "First aid for the USMLE Step 3" on your list. Do that book twice too. Personally I fired up a question block on Chapter X of reading something, and then read it again afterward.
Another thing I'll throw out--I'm wondering about your test taking stamina and conditions. If you were able to do step 1 and 2 I can't imagine that's an issue. but if you've failed something, that does put an awful lot of pressure on you the second time.