99 civic p0505, end of my rope

Hi all, I have a 99 civic LX with a d16y7 and manual trans, I’ve had the p0505 code for about a year now and have tried many things including:
-Cleaning the IACV
-New IACV
-New o2 sensors (they were 20 years old anyways)
-Checked TPS
-Checked output of coolant temp sensor while at operating temperature
-Checked MAP sensor
-Checked extensively for vacuum leaks
-Bled cooling system, following ETCG’s guide
-Swapped in known good ECM
-Even ran wires temporarily from IACV to ECM to see if it had a wiring issue
-IACV is now blocked off
I still dont know whats wrong.
When the CEL is lit and I come to a stop at a traffic light if I sit at idle for about 20 seconds or more without giving it any gas to bring up the RPM, then when I pull away from the stop the engine becomes violently harsh and jerky when letting on and off the throttle. It is most noticeable in lower gears, but present in all gears. The jerkiness is to the point where I feel the engine mounts are gonna break (none are broken as of yet). The issue will not occur until the CEL is illuminated and can be fixed temporarily by turning the car off and on again or resetting the CEL. If I rev the engine a bit while i’m stopped then the issue will also not occur. when the issue is happening, while i’m stopped, if I rev the engine then it will go up to 1.5K and hesitate until i give it much more throttle.
This issue was present even before I blocked the IACV and i did so because the car was idling at about 3K with the idle screw all the way closed. I have a feeling that these two problems are related but I cannot seem to find a cause, the last thing I want to do is start throwing parts at it.

All help is appreciated, I will make a video showing the issue and update the post. If my post is hard to understand please let me know, I wrote this at 3am and im tired.