Chrysler Neon 2002 Engine Cranking but Not Starting

Hi, So I just bought a 2002 Chrysler Neon two days ago, and it recently just passed annual inspection. It has been running just fine, except for a screeching noise while starting, as if a belt was defective. Today, I tried starting it multiple times and it would turn over but not start. I had a mechanic friend come over and look at it, and he checked it all. It's getting spark in all the plugs, it's getting fuel with great pressure, and it's getting compression. He said it sounds like the timing is 'off' but the timing belt is just fine. Everything seems to check out but it just will not start. The engine light is on while running, so the seller and I checked with a obd scanner and it says that Bank 1 is reading rich. I read in another forum that my catalytic converter sensor might be bad, but I am not mechanically inclined so I wouldn't have any idea.