Stupidity -
I've always wanted to believe if we live long enough, experience will outrun stupidity. Like many SOCers my tune up routine is muscle memory, uh, check that, rote.
Having the clutzy gene, whenever I take off the air cleaners, I wad small rags, and put them in the carb stacks, so I don't gracefully drop something in the carbs. This works well, unless you forget to take the small rags out when you restart the car.
After blurting out dirtyphilaramicpacaloomis!!, I ordered caps to cover the carb stacks, they are bright red, though not stupid proof, less likely I will miss taking them off.
Actually, the language I used was so harsh, the neighbor's cat gave me a dirty look.