I just got the yesterday. It is a 1989 560 sel. It had sat for a year before i got it. I drove it home about 160 miles. Running down the road it seemed to run fine. The problem is with idling. It seems to be missing a little. No smoke or any thing does not seem to be flooding out nor does it starve for gas when you take off. I put new plugs in it today and it runs a little better going down the road but gallops at idle. Looking at the cap and wires thay look fine . But how do you tell if there original. there is some valve train noise on the passenger side of the car. any ideas on the missing? the car has a tad over 115,000 miles on it