jazzy1jz

I just picked up my 1jz sc300 about 2 weeks ago. It ran fine for about a week after I picked it up and then one day after it warmed up it starting misfiring right about at the point where you would up shift during normal driving. I did some research on here and online and i'm thinking it's the coil packs. I also asked the guy who had it before me and who actually did the swap and he also said coil packs. I took them off and checked them and 5 of the 6 have hairline cracks barely noticeable about a half inch long or so from the very bottom of the coil pack (nearest the plug). It only misfires after it's at normal operating temp, and between 2-3K rpms or under a slight load. Any other time it's fine, even at WOT. I was hoping to get some expert opinions since my only real option with the coil packs is to buy all new ones. I checked the plugs and they look fine. Here's a video of it misfiring:
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