Mazda 6 Service Manual: No.6 cranks normally but will not start

No.5 engine stalls-after start/at idle

No.7 slow return to idle

Other materials:

Mazda 6 Service Manual: Underbody Maintenance
Road chemicals and salt used for ice and snow removal and solvents used for dust control may collect on the underbody. If not removed, they will speed up rusting and deterioration of such underbody parts as fuel lines, frame, floor pan, and exhaust system, even though these parts may be coated ...

Mazda 6 Service Manual: Engine coolant temperature (ect) sensor inspection
Note Perform the following inspection only when directed. ECT Sensor Resistance Inspection 1. Drain the engine coolant. (See COOLING SYSTEM SERVICE WARNINGS.) 2. Remove the ECT sensor (located above the starter). 3. Place the ECT sensor in water with a thermometer, and heat the water gra ...