2005 Silverado misfire

Hi guys, really new to using a scope and interpreting exactly what's going on . Working on an 05 Silverado with a 350. Has p300 but in gear with my foot on the brake it localizes to number 8 . Friend replaced all of the coils, plugs, wires and a purge valve . I used a uscope and the secondary plug pick up. I really wasn't worried about my time and voltage settings , I just wanted to get the whole wave on the screen .
My question is to anyone who would lend insight is , the wave looks like a lean misfire as I compare to one in Paul's book other than I see no spark line at all , just the big scoop after the firing line . Then the massive spike thats higher than the firing line?
The truck runs but badly , I noticed that the truck ran better with the purge valve open which I woukd imagine meant it was running lean. I did a fuel injector balance and 8 dropped from 50 to 32 , as well as as 2 other cylinders at 32, 38 being the highest .
The waveform from the other secondaries was similar to the image attached which surprised me a bit that they all had a real erratic spark line ir none at all. Tomorrow I was planning to check for voltage and grounds to the coils just wanted to see if by the image anyone could lend some insight that would be greatly appreciated.

Well done making use of the uScope for secondary testing.

The image you posted definitely suggests a lean condition. BUT, when was this capture taken? Idle, off idle, under load? Cold, hot? It matters for waveform interpretation. If possible, it'd be great to see more detail at 2ms/div or 1ms/div.

Injector balance test results are also a red flag for an injector problem, IMO. It's not unusual for the injectors at the ends of the fuel rails (like # to get clogged first. Was the idle and loaded fuel pressure reading OK?

With this YMM, it's also very possible to have leaking intake gaskets (the ends tend to leak first, too :lol:) on top of an injector problem. How are the fuel trims at idle and 2500 RPM?

Thank you for your reply Tyler, much obliged. The image was at idle and the engine was operating temp. The LT on bank 1 was -20-22 and bank2s upstream was fixed rich. New upstreams will be in tomorrow. I was hoping it was cross reporting the banks and in second sight could have checked global to confirm. Figured it had to come out one way or another and no better time to make sure the cat wasn't plugged. What I forgot to mention is it misses in open loop also. Intake gasket would affect both and knowing now they ain't the greatest.
I'll take some more images at 2500rpm,it was quite easy to share on here plus learning what even a little scope can do is is amazing . That little thing can be out of your box and powered on seconds
Also I'm old and forgetful , only took fuel pressure at idle lol , Will put a load on it tomorrow also and recheck,will also go for better detail ar 1ms or 2, thanks again

When I went back to the truck I smoked it first thing and both sides were spewing bad . Wasn't hard to find as bad as it was . The uscope has its limits but was nice to see what was going on with the secondary that fast. I have a little mp808 scanner but with a fixed rich O2 the scope got me further without having to replace it first .
Thanks for the info!