I found it. It was on the far left side behind the glove box. It even says Idle Speed Control. DUH. I have read about re-soldering the connections, so I'm going to give it a try. I hope I don't ruin it.
I hate to give DIY a bad name. You must have outstanding patience to deal with idiots like me who like to fix their cars with barely any idea what they are doing. But sometimes we figure it out and it's extremely rewarding for me to fix, repair and maintain things, especially my cars. It fascinates me to the point that I fantasize about changing professions and become a MB Service tech. Maybe I don't have the ole gray matter... I'll let you know what happens with my SL.
'85 SL500 Euro