When accelerating it starts to splutter and slug until getting close to vtec, I've narrowed it down to the o2 sensor, when it's unplugged and the engine light pops up it runs fine with no issues.
However, I brought a brand new o2 sensor and put it in and the same issue occurred and I tried another o2 sensor off the same motor. Whenever it is plugged in starting the car after awhile it drops down to near 100rpm looking like it's trying to relearn the idle but it does it every start and between stopping when driving here and there.

 

Still have the stock cat converter installed or is it straight pipe?

if stock catalytic then it could be clogged. Any other codes pop up?

 

No other codes popped up and cat's been deleted just have a what would be a pre cat o2 sensor

 

Try cleaning out your IACV with throttle body cleaner

 

Is this OBD1 or OBD2?
How many O2 sensors are connected? 1 or 2?

Make sure the correct upstream 02 sensor is plugged in, If you have a OBD2 and are using a cat delete most likely you have 1 O2 bung in the header or test pipe so make sure that O2 sensor is plugged in the Up stream bank1 O2 sensor plug, Bank2 can be left deleted but this will usually cause a check engine code but has no affect on performance. Check the wiring to the 02 sensor has no breaks. If the cable touches metal it could short out which is what it sounds like,

check the harness and look for any cuts in the wires or plug. Unplug the neg battery to reset the ECU after connecting the O2 sensor plug when you check for any breaks or damage to the harness.

 

I'm gonna have to go over the harness, the loom is obd1 but the motor is obd2 with a obd2 ecu so it must be a wiring issue

 

The ECU will look for that second O2 sensor, the harness plug comes out from under the car right above where the cat is usually. The other harness for the bank 1 O2 is right near where the thermostat ground is.

Or run a OBD1 ECU with a jumper harness .

 

Oh yeah this does seem like it could be the issue! But just to make sure before I got ahead, if I only have the o2 sensor that I have plugged in it won't throw a check engine light but if I unplug that one it does and runs fine. Either way it changes without their being a 2nd o2 sensor

 

I think when you unplug the 02 sensor the ECU goes into open loop so now the ECU will rely on set fuel tables, normally the ECU will be in Closed loop, Closed loop means the wideband/ O2 will try to control ur air fuel, so it makes sense why it runs better when you unplug the O2. Now it could mean either A. You need both O2 sensors working for the ECU to run properly or B. The O2 sensor you have is bad and needs to be replaced. or C. you need a OBD1 ECU so that it doesn't look for that second O2 sensor.