New radio but lousy AM

[garyj]

I decided to upgrade the sound system in my 1999, gradually. Last year I replaced the amp which helped. Today I replaced the radio with a Pioneer DEH-P5900IB. I was pleased with the results but the AM reception is terrible. I know that this seems minor but I use AM for traffic reports, news and sports. The installer told me later that this was common with aftermarket radios. I guess no one under 30 listens to AM anymore. Any thoughts? Help.
I was also thinking about replacing the speakers in the instrument panel but getting ones to fit the speaker grille was going to require some modifications so I decided to pass for now.