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: Generator removal/installation
Warning When the battery cables are connected, touching the vehicle body with generator terminal B will generate sparks. This can cause personal injury, fire, and damage to the electrical components. Always disconnect the battery negative cables before performing the following operation. ...

Mazda 6 Service Manual: Selector cable adjustment
1. Remove the center console. 2. Shift the selector lever to P position. 3. Unlock the lock piece of the selector cable (selector lever side) in the order shown in the figure. 4. Verify that the manual shaft is in P position. 5. Lock the lock piece of the selector cable (selector lever side) ...