I'm skimming here so forgive me if I missed this. Have you tried swapping or testing the coil pack? I understand you're describing something worse than a miss but this fall very close to the line of bad coil pack. I had this same thing going on. I could ease slowly into WOT and hold that but if I just aggressively got into the boost it would buck down hard. I chased vacuum problems and changed chips and did a bunch of stuff for a long time but the day I swapped out the cp it solved it instantly.