Yeah, that is the Overload Protection Relay, I've always heard it called the OVP too....oh well. If your 85 is like my 86, it is located right in front of your windshield (with the hood up obviously) towards the center and it has a read top with a clear cap and the fuse is under that cap. I have no idea (need other people to help me here), but could the idle problem be related to the idle control valve or idle computer?
'86 420SE Euro
904 Midnight Blue, Gray Velour
Dad bought it new, now I own it.
"A Mercedes-Benz is like a fine wine, it only gets better with age."