Take it to repair.
A lot of parts stores, such as Advance or Autozone, will check the codes for free. It is still up to you to diagnose the actual problem.
Scan the ECU with an OBD2 scan tool to retrieve the code that has been set.
could be the O2 sensors. My 97 does that when I pull a trailer. Put it on the computer and 2 of the 4 sensors were slow to react
No, oil level does not cause the check engine light.