I got the part number for the idle control valve on your 1983 280SEL(RHD)Mercedes. The number is: 000 141 15 25.The cost is $125(US). You can call Mike at IPCO Lilburn Ga. (Atlanta area)1-800-635-8590. I'm not sure if you can use 800 numbers outside the US. Email him at email@example.com
He does take credit cards, and will ship anywhere. Good luck.
Bill Lewallen Lexington,Ky.