The last few weeks whenever I come to a stop the car idles really rough and it doesn't stop until I take off. The exhaust pops out puffs every few seconds during that time. It also happens when I first start my car. From the MPG side, I used to get about 250-260 miles out of the tank and now am barely getting 200. I had the catalytic converter and air pump changed in Dec 08 and the car hasn't flooded on me since then and the check engine light hasn't gone off. Anyone know what could be the issue?

^well whats the check engine light code? that might help us out a bit

You can try some premix to see if it helps with the rough idle. You can try resetting your fuel trims to see if it helps with MPG. you may have a compression check in your near future.

When was the last time you replaced the coils, spark plugs, wires?

The check engine light has not gone off so I couldn't pull any code. I got the plugs change with the air pump and catalytic converter back in Dec 08, but haven't changed the coils.