as everyone else, i was having the same problem.
i got the achievement finally.
i played an exhibition game; mich v fl. 3 mins sliders default for the first half. the game was close 10-3 during half. then i set the sliders in my favors, i scored a td and to tie with 1 min left. then i let florida run down and score a field goal as time expired. and walaaah i got the achievement. so my theory is if you always win, maybe try to lose?? lol