That frame sounds about right unless you are holding some fat in your gut.
You need more then a good diet and cardio to keep your muscle. You need a good lifting routine along with that, a good HEAVY lifting routine. What is it, two and a half weeks before the Holidays?
You could do cardio 6 days a week with a good diet to lose weight, but honestly you really aren't going to probably get what you want within two and a half weeks to keep muscle and lose fat.