2000 durango check engine light is on at 36000 miles

any ideas? checked the gas cap, it was tight.

Just a shot in the dark, But I had a 2000 Durango 4.7 litre, It turned the motor oil into a nasty "froth"..... when this happened, the check engine light came on and my truck began running real rough. I read somewhere that there is a problem with the intake manifold, and that dodge acknowleged the problem in a service buletin but would not recall the item.
Like I said, I'm just taking a shot in the dark. This was the problem with my Durango. It made me mad enough to get rid of the truck. (check the inside of your oil fill cap for the white froth)