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: Intermittent concern troubleshooting
  Vibration Method 1. If malfunction occurs or becomes worse while driving on a rough road or when engine is vibrating, perform the steps below. Note There are several reasons vehicle or engine vibration could cause an electrical malfunction. Some of the things to check for are: ...

Mazda 6 Service Manual: Tire Inflation Pressure
WARNING Always inflate the tires to the correct pressure: Overinflation or underinflation of tires is dangerous. Adverse handling or unexpected tire failure could result in a serious accident. Use only a Mazda-genuine tire valve cap: Use of a non-genuine part is dangerous as the correct tire ...