Conductor plate, TCM (already replaced), likely culprits. My 97, same trans, did the same thing years ago, went through 2 TCMs and 2 conductor plates before 200k (Thanks MB CPO!). Although, I would do a trans change (don't forget torque converter!) every 30 with MB-approved fluid on these versions. There should be some codes that direct you to the immediate, offending culprit.

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former: 83 300D, 97 C230, 93 400E

current: 08 C300 Luxury , 92 500SL