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: Settings
NOTE Depending on the grade and specification, the screen display may differ. Select the icon on the home screen and display the Settings screen. Switch the tab and select the setting item you want to change. You can customize settings in the setup display as follows: ...

Mazda 6 Service Manual: Add-On Non-Genuine Parts and Accessories
Non-genuine parts and accessories for Mazda vehicles can be found in stores. These may fit your vehicle, but they are not approved by Mazda for use with Mazda vehicles. When you install non-genuine parts or accessories, they could affect your vehicle's performance or safety systems; the Mazda w ...