I had a thread going in the Quest forum, but it doesn't seem very active over there so I thought I'd post an update over here- now that I realize there is a separate engine forum. The original thread is here if you care to read it, but I'm the only one who has posted in it.

ignition-tune-up-and-state-inspection-t ... 97403.html

Bottom line, I may have found the problem today. While scraping up my hands and knuckles under the hood I started checking vacuum again, and I pulled the main line to the purge canister. When I plug it the idle smooths out and the miss goes away. I plugged the line and took a short ride, it's smooth but lacks the power it had previously. Could/would a cracked can cause this? I've never heard of one going bad but I suppose it's possible. It's only 20 years old with 185K on it- it's just finished breaking in, right?