The biggest hole in my endgames is probably simply deciding what to do. Should I hunt down his remaining pieces, defend against their pawns or attack with mine. Obviously there are clear situations but I find myself often not having a clear plan. If I have a passed pawn and my opponent doesn't, well there's no question what to do. Even situations though, it's one thing to not find the right move towards your goal, and an entirely different one not having a goal. I guess attack is the best defense. Tactics I'm usually ok with.