Improving on the Difficult Verbal section

Hi, after doing some ETS practice tests and the ETS verbal materials, I have noticed a limitation in my verbal performance. I am currently getting around a 160-161V and want to improve to 164-165 (or at least a 163 would be great). My issue is that, even though I have a good vocab bank (I encounter few words that I don’t know) and decent understanding of the passage, the questions I tend to get wrong, is usually in Text Completion and the ‘Check all the boxes that apply’ questions in Reading Comp. For text completion, I tend to make mistakes due to failure of fully understanding complex sentence structure and for the RC ticking the boxes questions, I’m usually able to get 2/3 ticks right (if the answer is 3 choices correct) or I’d pick 2 choices as my answer, when one includes the right choice according to the answer key and one doesn’t. usually the wrong choice that I selected has one word that makes it wrong, like I would over-infer or under-infer the info on the passage. Anyone has any insight for me? Much appreciated!