Mazda 6 Service Manual: No.7 slow return to idle

No.6 cranks normally but will not start

No.8 engine runs rough/rolling idle

Other materials:

Mazda 6 Service Manual: Curtain Air Bags
The curtain air bags are mounted in the front and rear window pillars, and the roof edge along both sides. When the air bag crash sensors detect a side impact of greater than moderate force, the curtain air bag inflates quickly and helps to reduce injury mainly to the rear outboard passenger' ...

Mazda 6 Service Manual: Child-Restraint Precautions
Mazda strongly urges the use of child-restraint systems for children small enough to use them. You are required by law to use a child-restraint system for children in the U.S. and Canada. Check your local and state or provincial laws for specific requirements regarding the safety of children ...