Poor reception in Monsoon System

I have a 2001 GAGT with the monsoon system, the problem I am having is I will have poor reception. It is like I am going out of the listening area but I am not. It is not an all the time thing either, it will be fine for a couple of days then all of a sudden no reception. I have bought a brand new Monsoon radio thinking that it had a bad wire in it. Still had the same problem. Checked the antenna cable on the back of radio that is fine. Check the plug on the antenna inside the trunk looks fine (actually on the way to the dealer to buy antenna base) don't know if this will solve the problem or not. We are at lost for how to fix this. Any help would be appreicated.

it could be a split in the antenna wire somewhere that you cant see between the dash and the radio