I'll bet if you check the stock gaps you find a wide range from 0.030-0.037. That's what I found on mine after delivery brand new. Consider checking them and getting them gapped consistently.
Interesting that Ford has supposedly narrowed the plug gap from factory for the 2015 (was 0.033–0.037 in. for the 2014). Inline with what people are reporting the OTC SP534 gap to be, 0.030.
