There are a couple common issues that I know of. Check your rear body mounts. If they collapse it will allow the body to pinch the fuel lines and vent lines. The vent lines go into the rollover valve on the pass side behind the rear fender. It should be normally open and allow the vented fumes to go to the charcoal canister. The valve is notoriously bad and can break and pinch the vent lines ot break free and allow fumes into the vehicle.