I HAVE A 98 RAG TOP & ON OCCASION I GET THE SAME BUZZING SOUND WAS TOLD IT WAS THE FUEL PUMP. THE SOUND IS AN ON AGAIN OFF AGAIN THING MORE PREVELENT IN TOWN DRIVING THAN ON THE OPEN ROAD. MY SOLUTION.....GET "OLE BLUE EYES" TO SING A LITTLE LOUDER.
I have a '01 Coupe that HAD a buzz caused by the resonance of the car. This may not be your problem but it is worth looking into. I first took it to the dealer who said it was a loose power window motor. They said they fixed it but the buzz was still there. The buzz sounded like it was coming from the drivers side door. I took it apart, put padding in it, but still had the buzz. I then thought in might be the top were in connects above the drivers head. I put some padding in the plastic molding but then the buzz was still there. I started to remove the interior body panels and just behind the panel were the seatbealt tensioner is located there was a small sheetmetal box. This sheetmetal box is the ant. booster. I flicked on this with my finger and there was the buzz. I thought it was just the two halves of sheetmetal coming together that was making the buzz so I added padding. Still buzzed. Then I took this box apart and there is a transitor board in there. I flicked it and found one of the resistors ( I think it was a resitor) was buzzing. I found it. I put padding next to the resistor and the buzz was gone. I put everything back together drove the car and for once this buzz was gone. It is amazing how such a tiny part can resonate and sound so loud and make it difficult to find. I hope this helps.