96 SW2 engine vibration when accelerating

My 96 SW2 has had a strong engine vibration problem when accelerating. I
feel it primarily in the accelerator pedal and steering column. When
cruising at a steady speed it purrs. The engine is otherwise running
perfectly
The dealer replaced the top engine mount which fixed the problem (mostly)
when at idle.
I've heard of a TSB that discusses a new type/design of upper mount ???
I've replaced the torque mounts and the transmission mount with no
improvement.

Van