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: Fuel Requirements
Vehicles with catalytic converters or oxygen sensors must use ONLY UNLEADED FUEL, which will reduce exhaust emissions and keep spark plug fouling to a minimum. This vehicle will perform best with fuel listed in the table. * U.S. federal law requires that octane ratings be posted on gasoline st ...

Mazda 6 Service Manual: Thermostat
THERMOSTAT REMOVAL/INSTALLATION 1. Remove the plug hole plate. 2. Disconnect the negative battery cable. 3. Drain the engine coolant. (See COOLING SYSTEM SERVICE WARNINGS.) 4. Remove the drive belt. (See DRIVE BELT REPLACEMENT.) 5. Remove the washer tank. 6. Remove the P/S oil pump. Note ...