Need help! Random misfire on stock ls3 swap

[Jshaffer123321]

Okay, so I swapped a bone stock 2010 camaro ls3 into my blazer, runs great under load but crusing I get sometime 300 misfires on multiple cylinders with flashing check engine light and afr goes very lean to 20.1 or so after light starts flashing, but before it does it stays pretty decent between 13 and 15, I haven't messed with settings yet because I'm not sure where to start. Timing advance seems high at 45.5 degrees, STFT is all over the place as well -20 to +20 LTFT is at 0, I'm assuming MAF needs adjusting as I built the intake, any help would be appreciated.

[5FDP]

If the intake tube is larger than the factory tube, it must be tuned for.

Are you running the correct fuel pressure too??

[Jshaffer123321]

I'm getting 60psi on the gauge and doesn't move while driving. And for the intake not sure of factory diameter I used 4 inch which I'm assuming is bigger then stock.

[B52bombardier1]

I currently have a random misfire on cylinder 7 - DTC P0307. Likely caused by a fuel injector gone bad with a very high 68 ohm impedance rather than the standard 12 ohm impedance - I will change that injector. You don't mention your fuel injectors but I figured I'd throw my situation in here as food for thought.

Rick