Tires really really matter. Personally I think it's probably 50-75% of the setup at least. Big blox, enduros, etc all do well on hard packed dust free tracks. That looks very dust, so they would basically slide across the surface instead of cutting through the dust and getting to the hard pack. This would cause what you stated, loose vehicle as the tires slide in the dust, lack of turning due to the tires sliding across the dust instead of biting into the surface, etc. Start with a tire change first, then start working on the setup.