Did you get your problem sorted? My 190E suffered similar symptoms, and a new voltage regulator and belt/tensioner was all that it required.

You might post this in the parts for sale forum along with the part number, if you haven't already done so.

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1992 300D 2.5T
1980 Euro 300D (sadly, sold)
1998 Jetta TDI, 132K "Rudy"
1974 Triumph TR6
1999 Saab 9-5 wagon (wife's)