Hi all. New member here. I recently purchased an '03 Bonneville in great shape with only 66K. It's been great the first 3 months. Sunday it ran fine. Monday morning it ran rough on startup and I thought maybe a sticky EGR since it was chilly out. Didn't smooth out as it warmed up so I put the reader on it and got a P0306. Since the failure happened suddenly, should I look at the plug, wire, or coil first? Thanks in advance for any help. PS I've owned 4 vehicles with a 3800 and this is the first time I've had this happen.