The tank capacity of a 87 300D is *checking manual* 18.5 US gallons. The Reserve light should come on at ~16.1 Gallons. The absolute most I've fueled up was 16.960 gallons. Even still it didn't have any stuttering problems.
When you removed your fuel cap, was there a hiss?
If so, then your breather hose (see picture) may be plugged and it can also contribute to this. I'm not sure about the 2 pick up lines in the tank, although I wouldn't be suprised since there's 3 lines that run from the fuel tank to the filters. All of these are under the car by the left wheel.
Also, are your fuel filters dirty? That may also be a contributing factor.