Chevy Mystery Misfire...After Engine SWAP?

After the frustrating Ford F150 EcoBoost no-start, the next diag *sounds* more straight-forward: 1999 Chevy small block that runs "rough", showing a Cylinder 6 misfire at hot idle. The engine is brand-new, and so are a lot of the parts under the hood. The owner loves his truck, and wants it to run PERFECT, so let s see if we can pinpoint the root cause of the misfire. IVAN S PICO WAVEFORMS: https://drive.google.com/drive/folders/1PxxhMTK5E3VvIgRaZdMcS8UGPhoVbyjQ?usp=sharing PHAD PRESSURE TRANSDUCER: http://www.pinehollowdiagnostics.com/new-phad-pressure-transducer.html Enjoy! Ivan