I have searched and searched for an answer to my problem, but I can't seem to find anyone with the same exact problem I have. My 1991 560SEL runs rough immediately after start up and sometimes takes a little bit longer than usual to start. The problem is usually worse once the engine is warm and has a miss on acceleration for about 30 seconds after starting, then it runs perfect. Idle is perfect and it even passed a California emissions test today with no trouble at all. It has a new fuel distributor, EHA valve, O2 sensor, spark plugs (the correct non-resistor ones), vacuum lines, and throttle switch. It also doesn't seem to have any vacuum leaks. I have also re-soldered the OVP relay, fuel pump relay, KLIMA relay, and idle control relay, yet this problem persists.

I'm concerned that perhaps I have an injector or two leaking after I turn off the engine. Is there a way to test this before I spend a load of money to replace them? I have also run a strong treatment of Techron through the system without much change. Thanks in advance.

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1998 E320 Wagon

1992 300D 2.5 TURBO

1991 560SEL M119.960

1986 300SDL TURBO

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1991 420SEL Parts Car