Check the rubber fuel line that comes up the fire wall. Where the metal fuel line is attached the rubber may have dried out and is leaking... My 98 E300D had a similar issue a couple of years ago and the Indie that works on my brother's 98 E300D simply cut a couple inches off of the rubber hose and re-attached the metal tube... The stumbling disappeared after a couple of days of normal driving...
If you haven't had your Intake manifold cleaned out, that will make a big difference in performance...

__________________
Joe

1998 E300D turbo 240K + Miles
2000 Dodge Dakota 122K + Miles
1992 Mazda Miata Autocross Machine 143K + Miles
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