Ok, the wife has a 98 caviler, and, lately, the gas milage is going down the tubs dramatically.

Right now it is all stock, has about 91k on the clock.

Last time I drive it, I noticed that it had a rotten egg smell to it, and, the cat makes some ticking sounds.

I am, right now, thinking I am going to remove or gut the cat and replace 02 sensor(s), and, run a tank with seafoam in it and replace the fuel filter.

Sometimes, when we try to start the car, if will turn over, and pop a few times and not run, then, the next attempt it won't start, and, then it will start and runs kind of hard.

I belive the motor in the car is a 2.2.

Did I get everything right or is there something else I should also check?