94 Taurus transmission advice needed

Replaced the VSS 3 months ago, running fine, no leaks, went to a highly recommended trans specialist.
Today when accelerating from 0 to 25 at 20mph I started feeling the
dreaded "shudder", like driving over a cow grating.
Are we talking torque converter? Clutch? Electrical problems?
No check engine light on so far. Thanks in advance
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Impending planetary gear failure. Plan on a new transmission.

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