Oil on spark plugs is the result of piston ring blow by, correct?

I did a scan on the car today and I got these misfire history readings:

Cyl1# 5
Cyl2# 442
Cyl3# 150
Cyl4# 17

At what point should I be concerned for the longetivity of my motor? Pistons/rods were always in the plans anyways.

If someone were to strip the threads of the head while putting in spark plugs, how would one fix this problem? I can never get the in-boost afr's to match up with what I'm commanding. I think all these problems are related.

Opinions?