#7 misfire help

[57jettruck]

Hey guys been having an issue with my car lately. It’s an ls3 car with cam, headers, cai, and a 150 shot. Here’s the issue, car was running fine and I had parked it for about 2 weeks while I was out of town. I canme home and went to driving it and all the sudden it started missing but didn’t throw the cel until the following day. Code was P0357 which is #7 coil pack malf. Anyway I had new parts already so I went ahead and replaced the coil on that cylinder put new plugs in and wires. Also I read the old plugs and they all looked great. Anyway put it back together and the car ran awesome for a few short trips. Then today on a longer drive it was driving fine then boom cel came on started missfiring again. I read the codes again and it’s the same code only this time it was accompanied by a P219a which I’m assuming showed up because of the misfire. Anyway I’ve checked over the wiring and I can’t find anything of concern however I did not unwrap any loom as I didn’t see any evidence to need to do so. Also while I had the plugs out I also scoped the cylinders to look for any evidence of cracks or damage being that I am running nitrous. However I’ve only sprayed the car about 6 short bursts not even 1/4 mile on any of the pulls. Also the car doesn’t misfire constantly only under light throttle input if I put a decent load on the car it doesn’t miss at all. Any advice would be much appreciated guys thanks.