2003 e39 525i rough idle

[fro3and5series]

Friends,
This morning my e39 was idling so rough it felt like it was runing on oval wheels. I checked the codes and I get misfires on cylinders 1,3 & 5.

After letting the car sit for 2.5 hours, I started it again and it idled smoothly. But was still displaying fault codes for misfires on cyliners 1,3,5. Since I do not want to destroy my catalytic converter, I'm not willing to drive it until I can check it out. Any thoughts on what it could be?

I'm thinking spark plugs or ignition coils. But all three cylinders on one side are out. what else could this be?

Thank you and I look forward to reading your responses.

[witeshark]

Also worth a look are the mass airflow sensor, and a look at the intake ducting for cracks.

[fro3and5series]

Thank you for the tip!