Mine did that tody for the first time EVER. Only once, after the engine was warm and I just restarted it. It was surging between 1000-1500 RPM (I think) and would not idle below 1000. I did not have patience with it and let only occur a few times. I put the car in gear and drove off. The darn thing actually stalled out once!!
The symptoms have not returned since then. I'm not sure what it could be, I hust rebuilt the engine and got it on the raod two weeks ago. It had been running better that it ever had.
'05 E320 CDI - 86,000 miles
'86 300SDL - 360,000 miles
'85 300SD - 150,000 miles (sold)
'89 190D - 120,000 miles (sold)
'85 300SD - 317,000 miles (sold)
'98 ML320 - 270,000 miles (sold)
'75 300D - 170,000 miles (sold)
'83 Harley Davidson FLTC (Broken again) :-(
'61 Plymouth Valiant - 60k mikes
2004 Papillon (Oliver)
2005 Tzitzu (Griffon)
2009 Welsh Corgi (Buba)