To be honest, I looked up the NGK T7340T-08 plugs and it had only been recommended for the current models of skylines in Japan. The current models are running some VQ series engine I think. I am pretty sure they were the culprits, cause with the new plugs it took one look and tweak of the CAS to get it started.
In any case, I will examine the tensioners and belts one more time just to be sure.