Well after checking everything under the sun a good old fashioned compression test revealed zero compression on number 2 cylinder. Pulled valve cover and found broken valve spring. Replaced spring on the the vehicle and runs like she used to again.

Thanks everyone for their input on the problem.

 

Were you getting any valvetrain noise from that broken spring?

 

No valve train noise at all, which I was surprised about too.

 

I don't know what the cause is but once every year when it starts cooling off weather wise my vehicle does the same thing with the same exact code, I carry an extra plug, and replace number 7. and all is fine until next year. i just chalk it up to some design flaw, mechanic has no explanation for it. something causes the plug to burn out prematurely.

 

How's your plenum?