The check engine light on my 1998 Honda Civic LX 5spd just came on a few days ago. I followed the tutorial to find out what the problem was (using the technique from here: https://honda-tech.com/zerothread/1901557) and I get error code 45.

Code 45 corresponds to "Fuel system too rich or lean." What could be causing the problem? What else can I check? I did notice today that when I initially started the car, it almost kept stalling (I have no tach, but I could here the RPM's bouncing very low which made the car jutter a lot).

Also, I noticed that the ABS light was also flashing. I get code 16, 18, 54 and 61. I have no idea what these codes correspond to since I can't find a chart online that lists the problems associated with these codes. Can anyone help?