Nothing wrong with 7 heat range and gapped at 0.8mm, even on a stock engine.
Try disconnect the O2 sensor, when they're dead generally the stock ECU goes a bit hay wire and pulls out heaps of fuel from the trim tables. If your hunting goes away, time for a new stock o2 sensor OR a Haltech (or Nistune or Adaptronic or a Vipec, etc.)