Hi everyone,
The shop replaced the coil yesterday, and the shaking has gone away. I hope that lasts. I did ask about the compression; the mechanic did not say they checked it, but he said that if that were the cause, I would notice the problem at all speeds, not just at idle or low speed.
Anyway, I second 1looselugnut’s comment. Thanks again to all who have commented. Your advice and suggestions have been very helpful!