2000 Honda CR-V stuttering and poor idle

Hey everyone, I have a 2000 Honda CR-V that started having issues a few weeks ago, when I was about to take a road trip I started the Honda to let it warm up for about 30 mins before leaving, it was about 20 degrees Fahrenheit out, and it started great and idled fine, after I came back outside it was a very random spit and sputter and when I drove it down the road 1st gear was great, shifted it into 2nd and it was sputtering like a machine gun, if I eased off the throttle to about 15% it would stop sputtering, but it didn’t matter if I floored it or eased into it, after about 15% throttle it would miss like CRAZY! No backfiring, just sputtering. It does this in every gear whether it is 1st through 5th. Now I have a funky idle as well, did not start to have this issues until recently.

I replaced the spark plugs and wires, as well as the distributor. It’s still missing. I also tried adjusting the valves since I know those can have issues, still no difference. It runs great when it is cold but once it warms up it is just a dog. I have a CEL for a knock sensor and a O2 sensor, I do not have a catalytic converter on this car, previous owner removed it. I unplugged the O2 sensor that was throwing a CEL to ensure that was not causing it. I occasionally get the P1399 CEL code but it is random, I have good compression on all cylinders.

I am at my whits end with this car, I am just trying to fix it up so I can sell it. What else should I try here? Could it be a faulty fuel injector or a weak fuel pump?

It is a B20 motor and a 5 speed manual.

Any help is appreciated.