You just bought it and it had a loose injector... sounds like the previous owner..PO.. also had fuel issues.

Id sure suggest the 'in tank' strainer / filter as the source of the issue. Do you have an under the hood filter ? and if so, is the fuel in there clear ?

If no to both... here is a very precise thread on how to clean the tank, strainer and fuel lines. Its more grunt work than hard and is where I would first be heading.

http://www.peachparts.com/shopforum/showthread.php?t=273491

http://dieselgiant.com/Mercedesfueltankremoval.htm

__________________
1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."