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: Contact Authorized Mazda Dealer and Have Vehicle Inspected
If any of the following warning lights or the indicator light turns on/flashes, the system may have a malfunction. Contact an Authorized Mazda Dealer to have your vehicle inspected. ...

Mazda 6 Service Manual: Floor Mat
We recommend the use of Genuine Mazda floor mats. WARNING Make sure the floor mats are hooked on the retention pins to prevent them from bunching up under the foot pedals: Using a floor mat that is not secured is dangerous as it will interfere with the accelerator and brake pedal operation, ...