My experience with these things are that noise or static has a source. It could be ignition noise(spark plugs firing, alternator, etc.). You may have a situation of inadaquate grounding. Poorly grounded wires act like antennas that can pick up radiated noise. Check all grounds including the ground strap under your hood that goes to your hood liner(which is conductive on one side). This helps shield the antenna from ignition noise coming thru your fiberglass hood. Mostly for AM radio though. Try re-seating the connectors on the radio. Can you hear the static change pitch with change in RPM? Does it go away if the engine is off? Keep in mind that an amplifier is just that, an amplifier. If radiated noise gets into the amp. via poor grounding, unshielded wires, it'll kick it out to the speakers. One other possiblity...assuming that at one time everything was working at one time, the spark that you referred to when the hot wire touched ground may have taken out a suppression capacitor in the amp. Try placing a capacitor between the +12V wire and ground close to the radio and/or amp. and see what happens. Radio shack can hook you up....BUT... make sure you get the polarity correct or you risk blowing the capacitor up. One more option, call a Ford dealer and ask. It can't hurt. Try strapping the radio and / or amp. case to chassis, basically making your own ground. Multiple wires to gound make a lower impedance path. This might help. I'll check with some more people tomorrow and see if I can dig up anything else.
