The most likely problem is that an engine mount, or multiple mounts, are broken or collapsed. This ’93 Accord has a very expensive, vacuum-actuated hydraulic mount which is activated by high manifold vacuum at idle. It’s very likely this mount which has collapsed.
I’ve got a ’93 Honda Accord while sitting at red light, or just ideling in the driveway, the steering wheel shakes quite hard. I’ve been up, down, in, and out of the column and yet I can’t figure out what’s going on. Any advice?