Mannnnn...thanks so much for this. My brain was feverishly taking notes. Exact same code. 2016 Highlander. I've already replaced plugs and coils with OEM a few months ago. Same misfire now back after couple thousand miles. I bet its its the injector. I'lll know tomorrow!!
Not sure what model/engine you have but if it's an older V6 Toyota/Lexus you may be able to get to the #5 injector and test it with a multimeter.. Without taking the intake manifold out.. Back right just left of throttle body.. I was able to diagnose a P0301 a few years ago on a V6 Lexus that way.. Here's the video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE--oAeZfr4OxI.html
