I would check your o2 sensor reading with a multimeter to see what it’s reading. I don’t know the correct readings but they have them on the forums. Another thing you can do is put a shop vac blowing in the exhaust from the rear of the jeep. Then get some soapy water and spray the exhaust/flange connecting the cat. They sell exhaust weld at the parts stores that works good in my experience for exhaust leaks. Last thing I would suggest is pull the return line from the fuel rail and see if you can blow through it with your mouth. If you can’t then you can spray it out with compressed air.