PROBLEM RESOLVED -

For those that may run across this thread in the future, my issue turned out to be the 25 cent 10-AMP ATC Fuse in the overvoltage protection relay (OVP). I suspected this to be the case because of the odd "burp" that occurred when I was jumping the battery over the weekend.

It is amazing (but not necessarily surprising) how poorly the car runs when the OVP has disabled the various fuel/ignition boxes. The car would start fine but bog down badly after a minute or so -- to the point that it was dangerous to even try to pull out onto the road. After it warmed up a bit -- say five minutes -- it would accelerate, albeit poorly, and it was still missing badly. If it did stall, though, I never had any problems restarting.

For those looking for it, the OVP (at least on an '83 SL) is in the front passenger's footwell, behind the kick panel just forward of the door, and slighly below the glove compartment. If you remove the fuse panel cover, you MAY be able to barely see it at about the 2 o'clock position, but it was not (for me) accessible through the fuse panel cavity, and I had to remove the "permanent" kick panel to get access. It MAY also be accessible through, or after removal of, the glovebox cavity.

I happened to have a spare OVP from an earlier troubleshooting exercise, and simply pulled the 10-amp fuse from the known good OVP and popped it in the installed OVP -- so it seems that the installed OVP was not fried -- just the fuse. I plan to start carrying a spare 10-amp fuse in the car -- if not the spare OVP itself.

One can only wonder how many hours and dollars have been spent by unsuspecting owners trying to chase down the drivability problems caused by a simple 10-amp fuse.

Beware when jump starting from or to your car's battery, as the blown OVP fuse appears to be a common result. But I do take comfort in the fact that the OVP does exactly what it is upposed to do, and possibly saved some of my high dollar black boxes! I'm glad to have resolved the issue.

Good luck.
Mike