99 cougar, crazy noise from speakers

ok here is the deal. i have a 99 mercury cougar i had a system in my car before i decided to modify the interior and everything worked fine, just the usual dimming of the lights. anyway now im putting in a whole new system,and im getting crazy noise from the speakers. everything was working okay when i was hooking it up, until i started getting that clipping/popping noise when i turned the power off . i did some research and came up with teh clarion eq that i had hooked up being the problem. so i bypassed the eq and was driving around for a day without it until i started getting engine noise from the speakers. I started troubleshooting it and thats when all hell broke loose. now im getting a loud buzzing noise. But this buzzing noise only occurs when the key is turned to the ignition. When its on acc, eveerything is fine. if i start the car, forget about it, the noise is a horrible squealing/engine noise. i am using a pioneer head unit and ive got a clarion 4 channel amp for the highs and mids. no sub and amp hooked up yet. I just moved my brand new red top optima battery to the trunk and i thought that was the problem so i moved it back and that didnt help. i tried new rcas, i even ran them over the top of the seat away from everything and didnt help. trie new grounds, new remote wire, didnt help either. i know its not the amp because i tried my old amp it didnt work either. I tried running the speakers straight to the radio and it worked perfectly. i also have an prestige alarm system installed, blackjax, pioneer navigational system and i even went as far as to disconnect all of these and nothing... i dont know what else to do, can someone please help. thought it was the alternator but it happens when the car is off too so that out of the question. maybe its the ignition, i dont know, can someone please help?

You have a ground loop. Please read the extensive grounding sticky at the top of the page. See also this: http://www.epanorama.net/documents/groundloop/index.html New Project: 2003 Pathfinder

yup   they were right. my rcas ground on the radio was messed up so i just grounded them to the radio itself and   everything is  perfect now,    thanks.