So I've been hardcore struggling with my blazer I just bought with 130k. The engine has a periodic misfire (according to live data the misfires occur on all 6 cylinders) will either stall or dip down to 200 to 300 rpms when you let go of the accelerator when the engine is at full operating temperature. When it's cold it only has a misfire and drives smooth (my first 4.3 v6 so what I think smooth is). Also found out it will not start if the engine was sitting off for a couple minutes after warming her up fully,

The only DTCs stored are C0225, C0226 (abs light on), b2961 (ignition was replaced at some point) and b0036. None of these help me

What I've done so far: I replaced the fuel pump due to it being original and the fuel gauge was out, I replaced all vacuum lines due to rot and loss of 4x4 (got 4x4 back after that), I've ran pressure/leakdown tests. 64 primed at service port snaps to 58 and holds above 55 for over 10 minutes, I've tested the ICM and redid the thermal compound.

Any help on this is highly appreciated.