Welcome John, We could use a bit more information to help narrow the field of possibilities. Tell us how many miles, what sort of routine maintenance has been performed over the years (if you know), and what's already been done in an attempt to resolve the issue. After 10 minutes when you say it runs great, what sort of driving are you doing? Stop-go city driving, or out on the freeway? You have two issues--hard starts and rough idles--they may be connected, but may not be. Either one of those issues can be the result of fuel system or electrical system malfunctions or mis-adjustments. Without knowing more, my top 10 list is:

1) OVP
2) Fuel filter & air filter
3) Plugs
4) Plug wires
5) Distributor cap
6) Rotor
7) IAC valve
8) Fuel pressure regulator
9) EHA
10) CPS

What can you tell us John?

__________________
1988 California version 260E (W124)
Anthracite Grey/Palomino
Owned since new and still going strong and smooth
MBCA member

Past Mercedes-Benz:
1986 190E Baby Benz
1967 230 Inherited from mom when she downsized
1959 220S Introduced me to the joys of keepin' 'em goin'

There are only 10 kinds of people in the world--those who understand binary and those who don't