Engine shuts off after driving for approximately twenty minutes

More than likely this is two things. First the canister has raw fuel in it. Then when the purge solenoid turns on to pull vapor into the engine it pulls too much and it floods the engine and it stalls. When this happens, you can try performing what is called a clear flood which is pushing the accelerator to the floor and cranking the engine. This will introduce more air and it should get the engine started.

To fix this, you need to replace the canister and purge solenoid. The canister has charcoal in it and once there is fuel in it rather than just fuel vapor from the tank it breaks the charcoal down and it gets stuck in the purge.

The canister normally doesn't pull in raw fuel unless one of two things happen (or both). First, if the fuel tank is topped off when filling the fuel tank. Meaning when the pump shuts off you continue to fill the tank just to top it off. The second is if you are filling the tank with the engine running. When you do this, the purge solenoid could be open when filling the tank which will pull raw fuel into the canister. So you need to be sure that the engine is off when filling the tank.

I included the procedure for the canister and solenoid. Let me know if you have questions. Thanks