I suck in technical positions.
These days in tournaments I am finding that I get excellent positions out of the opening. I am also playing the middlegame well enough to keep my excellent positions, a lot of them completely winning by the time the endgame comes around. However, I find myself unable to convert my advantage into a win, the technical phase of the game is my weakness.
To remedy this I have started doing endgame puzzles on chessimo again. Also, I am currently going through "Capablanca's Best Endgames" by Irving Chernev. The real meat of my endgame training though will come from the book "Excelling at technical chess" by Jacob Aagaard. I have his "excelling at chess" and "excelling at chess calculation" books, they are excellent but very hard. I plan to devote much time to this book over the next month. Hopefully this will pay dividends and help me win my section in the upcoming city championship again this year.
Another aspect of this training will be retooling my opening repertoire somewhat over the next month. I will be playing for queenless middlegames and generally trying to get more technical positions as white.