I still need help with my car audio system. i hate the noise coming from my speakers?

just yesterday i posted this same problem, i have tried all the sugestions i recieved. my system power and rca are wired oppositly. to and from the amp. they are well grounded. yest i have this annoying noise when my engine is running. what can i do, i have done all i know but no luck. is it my engine, my alternator, my battery or my car entirely. its a 99 isuzu rodeo.