Mine did this (badly) when I had a tight valve causing a miss at idle. Take a listen to your tail pipe at idle and see if the exhaust pulses sound smooth, or if you hear a chug, chug, chug.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine