Bad smell of gas leaks if you fill it up over a half a tank chugs sometime up hill..?

If the smell of gas is from unburned exhaust gas, I suspect the Ignition Control Module (ICM) is bad. The chugging supports this too. Be careful, if this is the case. The unburned gas can ruin the catalytic converter and the gas build-up can suddenly ignite and blow the exhaust system off the car. You need to evaluate if this is the case.

Another possibility is that the EVAP System is damaged and affecting performance. If the Check Engine Light is on, check for codes.