I'm going to give my 100% honest opinion and hopefully you won't take offense to it.
If you're getting a 40% that means you have a general lack of knowledge especially in the fundamental areas. Going through UWorlds bank of obscure and sometimes irrelevant questions isn't going to get you where you need to be.
You need to get Goljan RR/ First Aid/ Goljan audio and sit down every day with all 3 at the same time and do at least 1 chapter a day. With this you are going to improve all your basic knowledge plus get a super strong working knowledge of pathophys... One of the most highly tested subject areas on the test.
If you really want to jump 15-20% in about a month, and if you really work your ass off I guarantee that will do it.
Open up rapid review and first aid at the same time, and whenever Goljan talks about something new, pause... read it in RR and annotate the **** out of First Aid. By the time you get through the book you'll feel like you're smarter than you've ever been.
EDIT: If you just go through UWorld, you're going to feel overwhelmed and lost... Goljan will make you understand WHY you are picking the answer you're picking. Not just some random reflex reaction based on some buzz words you see. Because guess what, on step 1 day... there are no buzz words my friend. (Ohhh I got winged scapula but they still managed to word it in a way that I was nervous about my choice lol.)