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: General procedures
PRECAUTION (BRAKES) Wheels and Tires Removal/Installation 1. The removal and installation procedures for the wheels and tires are not mentioned in this section. When a wheel is removed, tighten it to 88-118 N·m {9.0-12.0 kgf·m, 65.0-87.0 ft·lbf}. Brake Lines Disconnection/Connection Cautio ...

Mazda 6 Service Manual: Cylinder head gasket
CYLINDER HEAD GASKET REPLACEMENT Warning Fuel vapor is hazardous. It can very easily ignite, causing serious injury and damage. Always keep sparks and flames away from fuel. Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injuries or death and damage. Fuel ...