Not that Chris Herbst needs anyone to "me too" his posts, but I couldn't help myself.

This concerns the motor shaking at idle, not noise or exhaust parts rattling or other metal on metal mistakes.

In my b21f car (79) I replaced the motor mounts alone with Scan-Tech parts I presume are the Swedish product. The idle system is not feedback regulated, no CIS or ECU like yours has, so the idle rpm is dependent on the quality of the warm up regulator or control pressure regulator. As mine warms up it runs through a very low idle period where the vibration is much more strongly felt in the seat and actually the whole body. The effect was not nearly as pronounced with the old mounts, but I replaced them because I could SEE the motor bouncing around in there. Big difference! But, give it a tiny bit of gas and the idle smooths.

Chris says the tranny mount should be replaced at the same time. I waited about 1000 miles, but the original (and I mean original!) was very soft compared with the Scan-Tech part I replaced it with. The idle vibration did mellow a bit, I think.

Anyway, my experience is explained by Chris' post.
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Art Benstein near Baltimore