Radio rushes, Audi 80 Avant

Hi, I hope now help from you. I have installed a DIN radio with my 80 he Avant. I listen to music with USB etc. funks everything perfectly, only the radio rushes constantly. I get no real reception. Have already changed antenna foot, where as is well known the amplifier sits, the antenna rod new, I don’t know any more. Does anyone have a tip what that can still be? Thank you