keep an eye on the clock. same goes for uslme steps 1,2,3.
check at a quarter, half, and three-quarter points at the least and make sure you are on pace. if you are behind, don't spend as much time on each question. it's better to go through all the questions quickly and being unsure, than being sure of your answers and not getting to the last 20. this is because there may be easy gimme questions or at least questions where you can eliminate 2 or 3 choices. making an educated high probability guess on all of the easy ones makes a significant difference versus randomly guessing or not answering the last questions.
finally, with clinical vignette questions, which may be a long paragraph filled with irrelevant distractor information, it is key to 1) read the last line of the question first (i.e. what are they asking) and then 2) look over the choices. then 3) go back and read the vignette, so you know what informational clues to look for. this was key for me. this may or may not work for you but give this strategy a try if time is an issue.