stumbling 420SEL
 

I have been tinkering with an intermittent stumbling problem with my 86 420SEL for several months. I finally called a tech at the dealer, who had some interesting ideas for checking it out...I had been looking at OVP relay, fuel system issues, and the like...he suggested a tired ignition coil or an intermittent charging situation due to worn alternator brushes. He also said to bring it by, he'd scope if for $50 and try to properly diagnose it.

If you're at a loss, you might as well get the $50 diagnosis before replacing parts that aren't bad.