1989 Isuzu trooper 4ze1 Spark plug 2 has oil residue on the electrode
 

I had my engine rebuilt a few years ago and never driven my car hard then one day it started smoking bad from the exhaust and motor I noticed a lot of blowby coming out from the valve cover and being sucked into the throttle body and also leaking oil from the dip stick I notice a spark plug had oil on the electrode I checked the torque on the heads and they seemed ok I am thinking it's the head gasket but need expert opinion - when it's cold and idleing it perfect no smoke or blowby any information is appreciated