My guess is you have (unfortunately) hit the nail on the head with the subframe mounts.

My car does the same thing, and I am not looking forward to doing the job myself.

The mounts have moulded in pockets (gaps in the rubber)
to make them absord more vibration, unfortuately this makes
them more prone to degrade.

Hope someone else has another (better) idea, as I am waiting with you.

Craig Amos
1987 300D Turbo, 280k mi

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