P0300 Mystery MISFIRE - Difficult to Diagnose! (Intermittent "FISHBITE")

Cylinder MISFIRES are generally straight-forward to diagnose... But sometimes they're NOT! This 2008 Pontiac G5 2.2L Ecotec is setting a *P0300 - Random Misfire DTC* at 244k miles. It runs a bit rough at IDLE, with an OCCASIONAL "hiccup" on Cyl 4...not a constant misfire. Under LOAD, everything is smooth and PERFECT! Obviously it already has brand-new spark plugs and coils. What else could it be? Injector? Vacuum leak? Bad valve? I have to pull out ALL THE TRICKS in my diagnostic arsenal to give the customer a 100% conclusive diagnosis. Even improvise a cool exhaust TAILPIPE PRESSURE PULSE test along the way! IVAN'S PICO WAVEFORMS: https://drive.google.com/drive/folders/1909JlHZ7_S7QrqeBPF7Rr2vTGgvCdh1a?usp=share_link PHAD PRESSURE TRANSDUCER: http://www.pinehollowdiagnostics.com/phad-pressure-transducer.html OTC 3398 Fuel INJECTION Pulse Tester: https://www.amazon.com/dp/B0002SR5OO?linkCode=ssc&tag=onamzpineholl-20&creativeASIN=B0002SR5OO&asc_item-id=amzn1.ideas.UKPVIGM4POWZ&ref_=aip_sf_list_spv_ons_d_asin TESLONG NTS500 DUAL CAMERA BORESCOPE: https://www.amazon.com/dp/B07SQ4FLYX?linkCode=ssc&tag=onamzpineholl-20&creativeASIN=B07SQ4FLYX&asc_item-id=amzn1.ideas.BH34H8T28VY4&ref_=aip_sf_list_spv_ofs_mixed_d_asin THINKTOOL PROS: ******TOTAL $150 OFF!!**** https://www.amazon.com/dp/B08SWH2KP4?linkCode=ssc&tag=onamzpineholl-20&creativeASIN=B08SWH2KP4&asc_item-id=amzn1.ideas.NHZL00NIDEPF&ref_=aip_sf_list_spv_ons_mixed_d_asin Enjoy! Ivan