its not the system thats at fault, we've tried 4-3-3 and had the same problems, there is just so little urgency, movement and ideas when we get into that final third, we seem to slow down to walking pace the moment we get near the oppositions goal unless Hatem is in charge.
We've only played 4-3-3 once, which was the second half against Spurs. The games you refer to were fairly negative and defensive 4-2-3-1s, where the emphasis was on not losing the game.