What codes are you actually getting? Also, I don't know where you are located, but if it starts with starting fluid, that leads me to believe there is a fuel pressure issue or the engine coolant temp sensor is not working properly.
The coolant temp sensor signals the PCM information about the coolant temperature. If it says it is 40 below 0, the computer will dump fuel to make it run in those conditions. If it is actually 50 degrees, it will flood itself out. Also, the exact opposite can happen.
If you have a live data scan tool, before running the vehicle, see what the ECT is signaling the PCM. It should be very close to ambient temperatures.
Here are two links you may find of interest. Please understand, this is a theory based on your description.
Also, if you do have a live data scanner, let me know the short-term fuel trims when the engine is at operating temp.
I will watch for your reply. Also, I am assuming the fuel pressure is correct since the work on the system was done. If you haven't checked fuel pressure, here is a link that explains in general how to do it. Most parts stores will lend you the fuel pressure gauge needed for this test.
Take care and let me know what has been done so far, the codes, and anything else you can think of that may help me. One last question. Let me know if the vehicle has run normally since the O2 sensors are no longer connected and the catalytic converters were removed.
Monday, January 2nd, 2023 AT 9:11 PM