"Buscar los tres pies al gato" = To look for the cat's three feet

This widely used expression means to be looking for trouble when there is none. More colloquial equivalent English translations would be "If it isn't broken, don't fix it" or "to split hairs"

"Deja de buscarle los tres pies al gato. Vas a terminar liándolo todo más" "Es una persona que siempre le busca los tres pies al gato"