I'm not quite sure what your plan is. If your plan is to work and study for the MCAT, sounds good, many people do it. Working/volunteering as an EMT is pretty common for pre-med students.
In order to better assist, it would be useful to post what you background is, cGPA/sGPA, previous MCAT score, programs applied to and more importantly for advice on the MCAT, how you prepared prior to taking it. I am not an expert on the MCAT as I have not taken it, but I imagine with this information you will get more replies to your post.