Is oil pressure gauge pegging when you accelerate? If not, could be oil pressure (flow to the heads) problem. Like Lee says, could be timing issue, check the timing. Could also be fuel octane, however i always burned regular in my 380 SE with no chatter; try a different brand. How many miles on your timing chain?

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65 190d sold
85 380SE sold
87 560 SL 180K
84 380SE 96K (mint)