Starter/Starter Fuse Problems..

I currently own a 1995 crown victoria that was once a deputy sherriff car and a few days ago it seemed like the ignition was stuck in the engage positition and although the engine was idle it kept jumping as if it was trying to start. I cleaned the terminals, had the battery checked, changed the ignition switch under the steering column and had a local shop nearby look at it. They informed me that although my started passed a diagnostic test at advance that it was bad and blowing a fuse, now the problem is i dont know where the fuse is actually located. The started wasnt mounted with the three bolts when i got it and its given me problems before, the mechanics at the shop said that i should replace the starter and fuse and i should be good but i should buy the started from napa this time. Someone please help if you can, thanks alot