Ok, just a touch of an update. still having the problem since the part is $491, but I am wondering about the smoke. While the car does this little bit of hesitation that it does, I can see alot of gray to white smoke out the exhaust. So my question is what is the smoke meaning, what is black smoke as opposed to white?

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1996 E300 D
1992 300D
1990 Ford E-350 7.3 Diesel AKA "the Deep Fryer"