Hi everyone, I am based in Newcastle upon Tyne, this my first Ford car after always owning German cars , anyway 3 weeks ago I bought 66 plate 1.5 diesel focus estate powershift privately on gumtree, the car done 126k, car was driving fine but I noticed last 2 days the car idling rough, I opened the oil cap while idle and I can hear kind of a popping crackling noise coming from inside the engine, secondly when I try to rev it ever so slightly it feel like it juddering doesn't make a difference if it is idle or moving from a stop there is a bit of judder at a very low RPM, can anyone relate to that or have any idea?

Thanks 

 

Best idea is to take it to a garage. The "popping" from the engine when the oil cap is off is nothing unusual, but the juddering could be anything, without having the car in front of us nobody will be able to say exactly what. 

Change the transmission fluid and filter, if you don't know when it was done last