There's a valve by the charcoal cannister above the differential. There's also a valve by the intake manifold but it's likely not that one. These cars also have a fuel tank check valve that you literally have to cut into the metal under the back seat to get to. Theres a good walk through video on YouTube for that though.
If you look up charcoal cannister replacement videos you'll see how to access the valve from the trunk but you can also change it from underneath if your hands are small enough.