The Red Devils, who currently sit 12 points clear at the top of the table, lost the Premier League title on away goals last year and Ferguson vowed that the feat would never be repeated.
Ferguson, whose side recently let leads slip against both Real Madrid and Chelsea, wants United to rediscover their form in front of goal.
"Where I think we can improve is that we don't seem to kill teams off," said Ferguson.
"We've beaten Wigan 4-0 on two occasions but those are the only matches we've won by that sort of margin. In a normal season, I'd expect a few more wins by that sort of distance. Last year, we won 5-0 against Wolves, Wigan, Bolton and Fulham, and we beat Arsenal 8-2, of course.
"We're not seeing those results this season, however. We haven't hit those heights. Hopefully, there's more to come and we'll discover that killer instinct that our teams in the past have had."
United host Reading on Saturday.