1988 sel300 3.0 engine low and rough idle when first started need some help

How long does it run rough?

Reasearch OVP and Coolant Temp Sensor.

Is your ABS light on?

__________________
-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/831799-post13.html
http://www.peachparts.com/shopforum/831807-post14.html

yes the abs light is on it takes about 10 minuts to start to run right and sometimes it just wont clear up

check the fuse in the ov relat, it is the one with the red top under the plastic cover behind the battery. if the 10 amp fuse is good, then the relay may be defective

sorrt srs light is on not abs light. what is ovp valve and its location the car warms up nicely installed napa fuel pump last year and just installed new bosh fuel filter

OVP is a relay...

...behind battery under black plastic rain cover.
It protects the cold start circut among other things

also suspect the water temp sensor...
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1FX0MB1RS1V30YBUYU&year=1988&make=MB&model=300-SEL-006&category=C&part=Water+Temp.+Sensor
...which is the primary imput to the cold start circut.

If the system is runniing fine when it is warmed up you might want to start with these components, lots have been written about them, use the search function:
http://www.peachparts.com/shopforum/search.php

__________________
-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/831799-post13.html
http://www.peachparts.com/shopforum/831807-post14.html