I have a friend with a ‘98 850 (non turbo). She is getting the check engine light code for sparkplug misfire. We have changed the plugs twice, and it still comes on.

The only new symptom is a very resonant exhaust sound. When she is sitting at a red light (Trans in DRIVE, and foot on brake), the exhaust sound makes your ears and head feel like they are inside a large pipe organ.

Of course, a guy would probably like that sound, but a girl does not! Do these two things have a connection? Could it be a Catalytic Converter problem or something with the emission system? thanks