What is involved in replacing spark plugs on a 98 chev cavalier? It has 90,000 mi and the "check engine" and "ets off" lights are on so I thought it would be a good place to start.

Easy job--just make sure and use the exact ACDelco plugs that came in the car. This is often the solution to the problem you are having. Platinum plugs should be replaced at about half the recommended mileage. Also, replace the fuel filter.

Instead of guessing, have a mechanic read off the diagnostic codes for you. Some of the mechanics around here in Georgia will check them for you if you happen to be getting another service, like an oil change. Although I definitely think you should change your spark plugs if they haven't been changed since, it's a lot easier to diagnose the check engine light if you can get the diagnostic error code first.

I just recently had my light go off and the mechanic thought it was a short from cleaning the engine cover after the valve cover gasket was replaced. He then checked the error code and found out it was an evap code. Something either to do with my gas cap (which I had replaced due to the other one being a bit old), a vacuum hose which the mechanic had already kindly replaced for free, or the actual evap canister. Anyway, long story short, I replaced the gas cap with a brand new cap meant for my car and it went away after a couple hundred miles.