I have an ageing Audi A4 1.9 TDI (03 plate 120,000miles) that has been a great car until a few months ago when it started to idle roughly intermittently. It has not lost power and the fuel consumption has not gone up. It pulls smoothly at all road and engine speeds. My local Audi dealer has fitted a new EGR valve and electronic engine mount but this has not solved the problem and I am now several hundred pounds poorer. They have given up and tell me it will cost "a lot of money" if I want them to look further. There are no faults showing on the diagnostics and the injectors are all working well within spec. They say it may be a DMF issue but that this is unlikely because there are no other symptoms. It does not smoothe out when the clutch is depressed and there are no knocks when pulling away or stopping the engine. They also say it may be the head wiring loom. Either way they say there is no easy way to check these things without significant cost. Can anyone help me get a diagnosis without spending even larger amounts of money?