I have a 95 E300 with 193K and just cleaned the in-tank fuel screen. The records from the previous owner show that it had never been done. My car used to "nail" when it was cold but I had gotten used to it. There was so much black slime on the screen that I couldn't see through it! After cleaning the screen, my engine is so much quieter and it never nails when cold! Not only that, but it seems like I gained 40 more HP! Just a thought, but if you don't know the condition of the screen, it could be starving your engine of fuel which can lead to "nailing".

Good Luck!

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1995 E300D - 193K and $28K in maintenance!
1964 220Sb - 318K, second owner
1997 Passat TDI - 190K and 47mpg