2000 Chevy Impala turn signals

My turn signals have been weird lately. Sometimes they work fine and others they dont work at all. While I am sitting at a light waiting to turn they will speed up or slow down then shut off completely and wont work again untill a get in my car again. I noticed this problem when I had two 12'' sub woofers installed. I have changed the fuse before but it always comes back. I have noticed that the fuses have been rusty. Could there be a bad connection?