Mazda BT-50 diesel ute
We live in Australia anbd purchased a new Mazda Bt-50 ute (pickup) in 2009. Within 10000km's of travel it started to run very rough, stopping only when the clutch was pushed in to change gears.
Mazda dealer was unable to see the big picture, refused to replace vehicle and after dumping several tanks of diesel he claimed was contaminated with water and causing the fault (the fuel filter has a water trap and was not picking up large amounts of water) and threatened to charge us $1000s of dollars to go over the fuel line and replace the lot.
The answer was finally located after a lot of visits to the dealer (over a dozen) and the lot of demanding from us.
Apparently there is a sensor on the clutch plate that was faulty, this sensor can cause the vehicle to run rough and not idle. Mazda will not tell anyone this.