Low Idle on 83 500SL
 

I'm thinking about replacing the distributor line, the number 8 plug is running very rich. If there was a small leak in the line would that cause the ilde to be low or would it idle higher?

Yes only #8, ok I will switch the injector to another cylinder and see if the problem follows it there. With the fuel distributor can I adjust the pressure to just that one injector?

They are not individually adjustable. Only one injector might be that the others are restricted by varnish/debris. There are tiny filter screens that may be plugged. Some people have reported good results with a couple tanks of Seafoam treated fuel. As always, Your Mileage May Vary.

I'm just tossing a random thought or two out. I tend to want to try the inexpensive things first.

Good Luck,
Scott