I have read that the NGK twin electrode plugs are laser trimmed to get the gaps to each electrode exactly equal.. If you pump enough energy into it, it will flash across both electrodes..

Actually electricity flow divides across multiple paths with current flow in inverse proportion to the resistance of each path..

Actually something similar happened to me with the SplitFire plus on my '94 3.0. After blowing the head gasket, factory recall, the tech actually told me something interesting. He suggested to only run "stock" plugs on any Toyota motor. The "extra spark" generated by SplitFire, etc. type plugs gets relayed to the ECU & knock sensor as detonation and hence changes the timing, in essence, changing the fuel mixture. He said he's seen many motors damaged or running poorly due to the plug change...that and different plug wires. And I have to agree. When I did all the mods to my '88 Runner 3.0, I originally had Bosche plus in it, along with MSD wires...I kept getting ECU codes, etc...put fatory plugs and wires in, problem solved.

So good luck with it.

Greg