Thats probably Power Service. Its one of the most readily available diesel fuel additives, they also have one called power service diesel kleen or something, thats specifically a cleaner, this may be the one you used. The VW guys love to run PS in their tdis it seems. I've had success with stanadyne's performance formula.

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2004 Ram 2500 Cummins HO
2000 Jetta TDI
1999 E300 (sold)