mach 460 question maybe bad ground.

There are 3 amps in the Mach 460 system. If I remember correctly, the amp beneath the radio controls the 4 tweeters; the left amp in the rear tray controls the two left speakers (front and rear), and the right amp in the tray controls the two right speakers. If you're getting static from the two bottom door speakers only (no static from the speakers in the rear tray), then I doubt it's either amp. The Mach 460 wiring does not have a special ground screw just for the sound system, so I doubt that's the issue.

Did you replace the door speakers with OEM Mach 460 speakers, or with aftermarket? The large speakers in the Mach 460 double as woofers and can't be replace with aftermarket speakers without losing the low-end bass.