After confirming compression. . .
Fix the map issue! That could definitely cause a multi cylinder miss.
Also check for,
oil in the plug wells
YES, YES, YES on the correct NGK plug
Wires should have dielectric grease at plug and coil ends
Quality fuel, and a regular dose of seafoam goes a long to.
Being a high mileage engine i would start my diagnostic with a compression test. I've seen more then a few people dump a bunch of money trying to get a slap wore out motor to run. . .