Nice write up on your car to tell us about what you have going on! I was thinking motor mounts right off the bat. Or was it the ding bat next to me one day, with his bass speakers turned way up. I then read deeper into your story.

Sounds like a low speed and occasional mid range speed miss. I do not like Champion spark plugs for that reason. They can make want to bang your head against a hood somewhere. Just my experience and opinon.

If your wires are a suspect. I would pop on a new set to rule that out.

Ignition systems are always the first rule in trouble elimination. Don't throw them out as it may be only one of them that is really bad and you can sort it out later for some training exercise fun.
I am always getting back a judgement for my trials and errors!

Scrape clean the the distributor cap terminals inside the cap or replace it. Inspect the rotor button carefully or change it as they are cheap too. The black or brown stuff embedded on the top goes bad, believe it or not.

The throttle body butterfly plate and housing may need to be cleaned as it will effect the idle ports to the distributor advance.

The smell could be a valve cover gasket or the rear plug seeping enough on long enough drives to be whipped up to the windshield cowling vents. Clean your flame trap as could be pushing oil out the rear main seal and that oil could be getting on the exhaust.

Check the dip stick area for it may have rubbed a tiny hole into the coolant hose that exit the fire wall there. I bend the dip stick tube away from them slightly for good measure.

Since you didn't mention it. Does the steam or smoke smell sweet or oily?

Good Luck
Phil