[davepl]

If it's a problem with AM, check the trim as Terry says.

If it's a problem with FM, try changing the height of the antenna until you get a good signal. There's a height for most antennas that works "best" for FM, and in fact, if you had an FM radio from the factory on a Camaro (or maybe a truck) you should have a fixed mast antenna that doesn't telescope because of that.

So if it's FM, try to replicate what the factory did by finding the "right" height and that might solve some of the reception issues.