I would say it's a common problem when you have a defective fuel accumulator.
http://catalog.worldpac.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=26R0X2XXH26Y0U2FFP&year=1987&make=MB&model=300-E-002&category=All&part=Fuel+Accumulator
If you installed a non-genuine cold start valve, I would strongly recommend that you replace it with the old original one.

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380SE 1984 <------- Totaled by flipping accident
300SE 1988 <------- Sold
Volvo S70 2000 <---- 4 family
Opel Omega 2002 <-- 4 family
560SEC 1989 <------ Sold
560SEL 1990 <------ Sold
560SEL 1991 <------ 4 my mother
560SEL 1989 <------ Sold
600SEL 1992 <------ Current

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