why are my door speakers cutting out?

[Jesse]

i got a new kenwood deck putting out 22 rms, twice as much as my old deck, and my speakers started cutting out at high volume but the volume wouldn't go away it would just get lower. so i thought it was my really old speakers and ignored it cause i was getting some new ones any way. i got 4 new kenwood door speakers 45 watts rms each and they are still cutting out. i am trying to figure out why this is happening cause i soldered all my wires, had the deck proffessional installed but people make mistakes so that might be it? i also have a 1989 car so maybe the speaker wires just suck. and also attached to all the doors are a coil of what looks like copper wire that my speaker wires run through for some reason ao i don't know if that could be it too haha, the maufacture did it. i will include a picture to show you what it looks like, and the one in the picture has the coil on the speaker mount but the otheres don't so i have to connect my new speakers through that coil thing, this is just a smaller version
http://s436.photobucket.com/albums/qq84/jesseastl/?action=view&current=IMG_1953.jpg

thanks for any help and sorry for so much writing..just wanted to be specific.