Check all the wiring behind the deck (stereo) I have had this happen and it pissed me off for a good 2 weeks straight

Turns out there is some sharp metal supports behind where the CD player / radio is and one of the wires was rubbing up against it and wore off all of the rubber insulation. And every time I hit a bump or shap turn the wire would touch the metal piece and short out the fuse. I suggest you do that because I had the exact same thing happening to me and it drove me nuts I still to thins day cant believe that I ended up finding it there.