Hey how are you
This what open loop means please read below
The open loop mean the car is still cold, basically when the engine is still cold and the Heated Oxygen sensor are heating up the PCM, get it Air fuel ratio from the ECT sensor ,map sensor ,maf sensor etc.. to keep car running correctly ,when engine warmed up and oxygen sensor heater came on and activated the PCM Should switch to the Oxygen sensors for these reading to keep car running ,so if you are no switching from Open loop To Closed loop After Sensors are heated up then the car is always running open loop, and in open loop ,obviously the pcm dumps more fuel to keep car running until engine warms up but if it is not switching then it will sputter ,runs rough misfire etc..
so the question is why is it doing that .
Now the Most common thing will be PCM issue ,wiring ,short ,loose ground ,you have pin out the pcm connector and run a continuity test on the wiring harness
not easy to do and time consuming and will need a level of experience to do that safely with damaging other systems
I m sorry to hear you have been Throwing parts at it , on capable scanner , what is the Fuel status showing , oxygen sensor readings ,upstream downstream, and fuel trims readings ,can you get me that , i can help you further on it and be more accurate for you
Please let me know
ASE Certified Technician