Thanks PM. Can you tell me what engine and chassis model my car is? Wikipedia says the car is an R107, but nothing re: the engine.

I pulled one plug last night and it looked pretty good - a little brown, but with a light sticky touch of something on one side of the electrode. The plug is a bosch super (wrote down the number, but it's out in the car right now). My mom had a bunch of work done to track down a fuel problem a few years ago (and about 2000 miles ago). I suspect they changed out the plugs and wires, since all looks very good, so I'm waiting for her to send me her file on the car before I bother with the plugs. I'll put some techron in the tank and put a couple hundred miles on the car and see if that helps.

The idle is only a little rough, you only notice if you are really listening for it. Do these cars have a bit of a lope at idle, or are they smooth like a sewing machine?

Thanks!