I appear to have a bit of a strange problem with the diesel engine at the moment, it's not a massive issue but it odd nonetheless. When the outside air temperature is 5 degrees or less the engine sort of feels like it's misfiring in one or two cylinders. I have an example of when it happens:
Start the car up, engine is idling fine no misfiring or surging
Set off at up to max speed of 20mph to the point where I get to the end of the road (approx 450 yards)
Trying to maintain the speed is difficult at around 1800rpm, because the engine and car surge back and forth as if the engine is misfiring
Engine is fine by the time I have pulled out of the junction to join the main road
I have noticed that taking it up to 2500rpm in 2nd after startup seems to clear the throat so to speak, and the engine stops surging, I have also noticed that it doesn't happen if I was to leave the engine idling for a minute or two.
Could it just be that the temperature is so low and diesel engines are rough as hell when cold?