TBI 454 Misfire

[wb292]

I’m battling the same issue with my 95 Suburban 454. You might try inspecting the white wire coming from the knock sensor. Mine had rubbed through the insulation with the blue wire next to it. This sent full voltage to the ECM and retarded the timing causing a misfire . Sometimes violently. I too have replaced everything imaginable. I purchased a scan tool capable of obd1 live data. But I could never really find any reading out of range. Now I have to advance the timing to 16deg with the timing wire unplugged to get it to run. I’m concerned I may have a stretched timing chain.