My engine is misfiring at all speeds and check eng. light on, sometimes flashes. on 2002 Chevrolet Prizm

Check engine light has been on for long time and eng. ran O.K.
Now when eng. is turned on it misfires at idle. It also misfires when I give it a lot of gas. What is the first part
that should be checked?

Asked by for the 2002 Chevrolet Prizm
plugs and wires. it sounds like you have neglected the service on this car if the light has been on for that long. i would go to a shop and get a real diag and a bid to put in good working order before something big goes wrong.