Here's what I changed; New oem wires, extendors, boots and changed to a hotter plug [NGK5 vs the NGK6 I had prior]. Moved to an 89 octane fuel from 91/93 [premium]. I read here somewhere that the 308 should run fine on 89 octane. I have a sputter on acceleration...say 3000-4000K and then it's gone. Never above...it runs very strong. Also idles fine. Where would you start?