Is that all it says on the plug ? I can't find "G1" as a type of NGK plug. The NGK plugs that are usually used as OEM are IFR6A11.
sorry stevie it says ngk 1r and 1fr6t11
Hmm, well, 1FR6T11 is not the same as the OEM NGK 1FR6A11. According to this page, the "T" and the "A" refer to different constructions of the firing end.
So it sounds to me like the wrong plugs were in your car, at least in that particular cylinder (where they all the same) ? Maybe having the wrong firing end is connected with the problem on the electrode ?