Poor game management. The Colts should have picked up the 1st down, instead, Manning went to the end zone then deep. By picking up the 1st down it would have made the field goal a little easier.
That was on 2nd down he went for it all, pretty good play actually, go for the throat and the win. The third down play was an incomplete pass to just last the markers. Can't really fault the calls on their final possession, though his final pass did kind of suck.
Indeed - I said the same thing at the time. They only needed two yards for the first down. They could have picked it up on a short pass and then extended the drive. They still had plenty of time.