Andy wrote:
Like I've said before, I've seen plenty of plugs (even new ones) that won't work once fitted and under load. Load isn't just WOT at low RPM, load is also operating load.

Plugs weren't swapped from L to R. I can try it if you want to see what happens

Andy, do you believe that these plugs are prone to fuel fouling? I have a mate that believes this same theory too, and for me I just can't fathom it, although I'm willing to believe it.

I will try new plugs today (and gap them!), I was told that they are new plugs by the previous owner.

How much do the plugs cost in the UK? They are AU$13.95 here, they had a price hike from $11.95 in the last couple of months no thanks to this economic crisis.