190E Idling Blues

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My 190e 2.3L developed an irritaing rough idle with a mild clicking sound from the valve cover. When the service interval came up, I took it to a local mechanic who have been doing Benz only for years. I was told that after a compression check they found the #2 cyl was not up to spec, lifter was bad (thus the clicking sound). My 190e has 120K miles on it, so the recommended valve job was carried out, plus fuel govenor was replaced (leaking), O2 sensor replaced, temp sensor replaced. When i got the car back, the rough idle was still there. After reading this forum for lead, I replaced the original OVP, kickdown relay, fuel filter and coil....still no solution to the rough idle. What else could be causing this irritating rough idle??? Any guesses or pointer. No loss of power or hesitation while driving. Rough idel only at light or when in P or R. Rough idle more apparent when engine warms up.
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