Join Date: Nov 2003
Location: Independence Ohio
I'm sorry to be the bearer of bad news, but based on the troubleshooting you have done, you more than likely have a bad radio.
The only other thing that can cause this exact symptom would be if one of the headset cables were pinched somewhere. Also, if you have a passenger audio controller, disconnect it and see if the problem goes away.
2002 Illusion Blue GL1800