2003 crown vic check engine light on and can't fill gas tank to fast or it comes out bottom of car?

Might have a leak in the fuel filler neck. either the neck itself has a hole (rust?) or the short rubber hose that connects the neck to the fuel tank is bad. Normally the fuel system is sealed, if the gas cap is loose, for example, that will cause a check engine light. I think you have a hole somewhere in the tank or filler neck that is causing this.
If you can examine it from underneath, you might be able to see the problem, look for stains from the gas. If you can see the problem, it should not be hard to fix.