In regard to plugs, sometimes new isn't always necessary, make sure they are gapped correctly is what is important.
Otherwise I'm not sure where else I can help so free bump.
Edit-Have you considered going back to an older firmware and map that was stable? Also are you able to get race gas in your country for testing purposes to rule out octane issues? (100+ octane).
Last edited by Jeff@TopGearSolutions; 11-14-2012 at 01:05 PM.