Wooah ... the idle control valve IS NOT connected to the fuel lines. It connected by 2 hoses which buses air to and fro the valves.
Its position in front of the fuel distributor but is NOT at all link to the fuel.
However, as much as we'd like to solve your eeeratik idle, I think you had better run a diagnostic test on the engine. The problem MAY not solely be the valve control because you did say the idling gets worse when the engines warmed up?
When you run your MB at cruising speed, do you experience any sudden jerk or loss of power?
126 tailed by a 203, 129 leading the pack.