Lets start with dtc codes:
P0175: system too rich bank 2
P0300: random/multiple misfires
P0302: misfire cylinder 2
Based on these codes and what you are describing, I would not be considering injectors, crank, or cam sensors at all. At least, not yet. You need to do some diag, don't just throw sensors at it.
Was it skipping first, then you changed the plugs? Or did you change the plugs then it started skipping? When you say it overheated, do you mean close to red or actually into the red? If into the red, how long was it there? Have you done a compression test on cylinder 2? Wet and dry? How about a leak down test? Did you verify fuel pressures?
I know it sounds like a lot to do, but you can rent most or all of these tools from parts stores and find procedures on line or YouTube. Diagnose the problem, don't just throw parts at it and hope something works.