How do you know a lifter is bad or it's just "lifter noise"? on 2003 Oldsmobile Alero

Check engine light started flashing, I could feel the car hesitate and didn't have a lot of get up and go while trying to accelerate from a stopping point. I can hear the lifter noise and checked my oil to see if it was low and it was on mark.

Asked by for the 2003 Oldsmobile Alero