Looks like you may have a problem with your fuel pump and /or the oxyen sensors. Cheap gas will contaminate oxygen sensors. Now you have to test the O2 sensors to see if the readings are flactuating between.01 to.9 volts when hot. If the reading are not flactuating, then the O2 sensors are contaminated and are rendered ineffective. Take it to a known garage and get it tested. Good Luck.