Mazda 6 Service Manual: No.4 hard to start/long crank/erratic start/erratic crank

No.3 will not crank

No.5 engine stalls-after start/at idle

Other materials:

Mazda 6 Service Manual: General procedures
PRECAUTION (SUSPENSION) Wheels and Tires Removal/Installation When a wheel is installed, tighten it to 88-118 N·m {9.0-12.0 kgf·m, 65.0-87.0 ft·lbf}. Suspension Links Removal/Installation Tighten any part of the suspension that uses rubber bushings only after the vehicle has been lowered ...

Mazda 6 Service Manual: Input/turbine speed sensor inspection
Caution Water or foreign objects entering the connector can cause a poor connection or corrosion. Be sure not to drop water or foreign objects on the connector when disconnecting it. 1. Disconnect the negative battery cable. 2. Remove the battery and battery tray. 3. Remove the air cl ...