Camaro1998Z/28

I have a unmodified pioneer avic-n1 with 90 edition discs. I installed it on my 1998 Camaro SS with Monsoon Sound System and everything works fine when its not moving, however when the car is moving, there is fluxuating radio reception. Its not the car, I just pulled a pioner avh-4000 from it which worked fine. As I move with the car the radio reception cuts out, but as you come to a stop the sound is 100% clear. Any ideas? The car does NOT have a power antenna. Thank you!