I used to work at Traffic jams and the common thing that I ran in to with fords was the factory ground was not good to start with. We started to run a ground 4g to og wire from the neg terminal from battery to the chasis. Also. ford uses a lower voltage signal for the amp turn on wire, so you have to put a resistor in line to do away with pops. Recheck your grounds. That is where I would start.