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: System wiring diagram
ABS (ABS/TCS) DSC FOREWORD Before performing the steps in Symptom Troubleshooting, perform the On-board Diagnostic Inspection. To check the DTC, follow the DTC Inspection steps. ...

Mazda 6 Service Manual: Replacing a Wheel
WARNING Always use wheels of the correct size on your vehicle: Using a wrong-sized wheel is dangerous. Braking and handling could be affected, leading to loss of control and an accident. CAUTION A wrong-sized wheel may adversely affect: Tire fit Wheel and bearing life Ground clearance ...