did any hear the conclusion to this drama? Did it turn out to be a coil, plug, injector, vacuum leak or ??

yeah, ordered a coild pack from Rockauto to replace the front 4 coils. I used one of the four to replace the bad one in the back and the misfire stopped.....
Still have crap gas milage but until I replace the exhaust, thank you GM for an all or nothing exhaust... I'll continue to have the low gas milage....