You might want to check your grounding connection. Even if it looks ok, appearances may be deceiving; you can unscrew the nut, clean up the contacts and re-tighten.

By grounding do u mean from the battery to the chassis?

__________________
198? 300D ???K - Future DD
1989 300TE 285K - traded in '12
1984 300SD 186K - Sold in 08
1978 300SD 330K - Died in 05

No. If that grounding was bad, your starter wouldn't crank.

There are several grounding spots within the engine compartment. If you follow any brown wire (I believe Mercedes uses that colour for ground wires across all models), it'll lead to a grounding point attached to the chassis. On my car, they look like an upside down bolt.

I found one under the windshield washer fluid container. It looked good, but it was causing issues, so I fixed it.
I had another one under the coolant overflow tank. This one was rusted, and was causing electrical nightmares like no horn, no right side headlight, etc.

I hope that makes sense.

Tudor