Have a 91 SL500 with under 70K miles on it. Recently it idles rough when I first start it up then levels out. At higher speeds it runs well until the engine heats up then it starts to miss when under load of going up hill or acceleration. After warming up it also misses when idling.

Anyone have any idea what is going on?

 

Check the distributor caps. They mount on the front of each Cyl head. They are coverev by plastic covers. Remove the covers then unscrew the 3 5mm allens in the cap and pull it back to inspect. The one on the passenger side is easy to get to. I bet you will find them green inside! If this is the case replace the caps and rotors. Also make sure the cam shaft seals are not leaking while you are in there. Good luck!

 

Thank you very much, I will do that.