I have recently purchased an '03 reg Mazda 6 2.0 (136bhp) TS TD. The car has done 75,000 miles. In my rear view mirror I can see smoke in the headlights of the car behind when going over 2000 revs. Now it has started stalling without warning. This usually happens at around 40mph whilst my foot is off the accelerator. I place my foot on the accelerator and there is nothing. If I place my foot on and then depress and hold the clutch down, the revs go down to zero and the engine has stalled. Releasing the clutch pedal whilst in gear then starts the car as a bump start.

Also, when the car is running idle at traffic lights, the engine has been known to just cut out. When this happens, sometimes I will turn the key and there is no noise. I can turn the key to click one and that's normal. Click two shows the normal lights on the dashboard. Turn the key further and nothing, not even the engine trying to turn over. I have had a full service and the cambelt changed last week. The smoke was there and a bit of stalling before the service. Are these two faults connected and what is it that is doing these two things to me?