I am having fuel system issues.

221: Fuel system compensating for extremely rich or lean air/fuel mixture at cruise.

231: Same as above just not "extreme".

232: Fuel system compensating for rich/lean at idle.

This car has a replaced engine recently. The same fuel issues existed with the old engine. The cylinders in the old engine were heavily corroded. Could these fuel issues be the culprit?

I have read some other threads and have some ideas but I have no experience working with fuel issues. Just basic fixes and maintenance: brakes, alternators, batteries, starter, oil changes, belts, etc.

I need insight on the possible issues and possible parts needed.

From my research i've found it could be at least an air mass meter, my googling only leads me to the mass air flow sensor part, can't find AMMs. Are they synonymous?

also could be O2 sensor, a combination of both and more.

My work commute is 30 minutes. I have a new job as a computer programmer and can not face extended time at the mechanic. I can maybe arrange carpooling for a few days tops. But have to drive this thing until I can get a feel for whats going on.

I need your help to point me in the right directions so I can talk to my mechanic asap. He is open Saturday and I am off.

Thank you.