Last time at the track the engine misfired at the end of track and mph was off. The Nitrous was low ,but gauge was still in the green. I used SCT to return to stock tune. On the drive home my A/F was 11.8 - 12.2. The CEL came on P0307. Cleared code , drove 10 miles to shop, CEL stayed out. On the Snap On scanner #7 showed misfires but note enough to set code, Long term fuel trim was adding fuel. I smoke tested intake for vacuum leak at #7 port,OK, checked compression -good- installed new plug reset fuel adaptives. Started engine and while warming up same shit happens, #7 starts to misfire and fuel trims start adding fuel, still no CEL. Plug was wet and fuel trims indicate #7 not firing. Stuck a spark tester in #7 wire and started engine. NO SPARK. My question is why with the #7 plug wire unhooked wouldn't the check engine light come on? Time to order intake gasket and pull manifold.