Are 5 AP classes too much for Junior Year on top of ECs?

I would push APUSH down: AP Language is a much better class to help with general writing and analytical skills for a STEM major than APUSH is. (I also hate US History passionately, but whatever)

Also, consider an elective? I know Psychology/AP Psychology or an engineering elective or something would be fun. People underestimate the value of mental health junior year, and taking fun classes with friends is vastly underappreciated, imo.