Well, I'm a single mother/college student who went car shopping alone. BAD IDEA! He got me!

I'm now stuck with a 98 Millenia that is slow on acceleration. so I took it to Autozone for diagnostics. codes were PO135, PO140, and PO300. I'm aware that 2 of these are O2 sensors. 300 is supposedly a random misfire detection (whatever that means)

My question is out of the 4 O2 sensors on this thing, how do I know which 2 it is? What do I need to do to fix these issues and what is the priority here?

Keep in mind that the car has been sitting for some time. I'm thinking maybe a tune up would be a good place to start. I did purchase a fuel injection cleaner but it's too soon to tell if it has made an impact. CEL is blinking! I was told this was very bad.

PLEASE, for the love of God, someone be honest with me and tell me what to do. Thanks!