Although I'm not familiar with this vehicle, you may have a fuel cutoff solenoid, which basically is an electronic switch that allows fuel to pass when the ignition is on, but closes and stops fuel passing when the ignition is turned off. If it is faulty or power is being interupted the fuel may cease to reach the engine periodically and the engine will stop. If you have one of these fitted, it will be a cheaper option to check this out first than the fuel pump or ignition chip. Also check that no air bubbles can get into the fuel at a loose joint or damaged fuel pipe.