Yr ignorance is yr problem, yr right.
The fact that you ask these questions demonstrates how little you know about how engines work and how much information an engine monitor provides:
And what about how an injector works and how you can tell on your monitor when the air filter is blocked. ...
The injectors to which I referred are those on an NA CMI engine. Those injectors suck in air through the screen at the bottom of the shroud on the injector. The injector needs to do that to atomise the fuel it is injecting. If the screen is blocked, the injector won't work properly.
But the usual maintenance induced failure is due to partial or complete blockage of the jet - foreign objects introduced into the system. That's easy to spot if you know how engines run and what the monitor is telling you: The cylinder either isn't working (no motion lotion) or has an unusual EGT for the mixture setting (because the cylinder is somewhere different on the lean curve than it usually is).
And then why if your engine was set 2 deg out why and how you found that.
Again, easy if you know how engines run and what the monitor is telling you.
In this case the CHTs were around 10 - 15 degrees C hotter in the climb than normal, straight out of maintenance. With the assistance of The Timing Fairy I discovered that one of the magnetos was advanced 24 degrees instead of 22. You would of course understand why advancing the timing results in an increase in CHTs...
Btw engines will vary up to 2 deg between services depending on what the age of the engine is. That's not uncommon.
BTW, a magneto that's set to 24 instead of 22 out of maintenance is the result of incompetence. That's not uncommon.
Tell us, yr right: Have you ever made a mistake?