Speaking from experience, studying for the MCAT really drained me. I was only able to work Part time on weekends and did some MA work once a week. I took the Berkeley Review all summer and basically had no life outside of the things I just mentioned. If you absolutely have to take classes while studying for the MCAT then you should probably drop either the EMT or research. If I'm being completely honest I would drop everything but maybe the scribing. It's ultimately up to you how much you can handle. I just got hired as a scribe too, so congrats!