Going off memory, its a 20A yellow fuse in the box underneath the steering column. I can check my stang after work today, but if you can't wait, just check all of the 20A fuses to find the bad one.
On earlier models (Pre-'94) the cigarette outlet fuse was under the dash.On 94' and up the fuse for this outlet is located within the Power Distribution box under the hood.It's a small black box on the drivers side just behind the battery.Remove the lid and the fuse you'll be looking for is a light green 30 amp fuse on the bottom row of mini fuses.It'll be on the right hand side.