It doesn't idle rough at all but, I did check the fuse on the ovp.
I read some of those posts about the solder cracks. I've worked on circuits boards in the past so, I can solder. I don't know where the idle control unit is on this car. There isn't much room between the engine and firewall, which is where I think it would be.
I don't know if this car even has one.
1983' SL500 euro