Yeah, it sounds more like a fuel delivery issue. I agree with those suggesting you check the injectors. You should also try to verify that you aren't getting any air in the fuel lines.

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'95 E300D ("Tank") - 231,000 miles
'79 240D ("Biscuit") - 197,250 miles (Sold)
'83 240D ("Ding-Ding") - 217,000 miles (Death by deer)
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"Back off, man. I’m a scientist” ~ Peter Venkman