What year is your car and what engine do you have?
I was going to suggest replacing your OVP, but on the older KE fuel injection systems, the engines will run fine with a failing OVP or even w/o the OVP.
1993 and newer 300TE's have the newer electronic HFM system, and could exhibit your problem with a bad OVP.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".