Get it properly tuned, basic stuff really. Check for bad spark plugs and replace with oem, alignment, Catalytic cleaning and fuel filter replaced.
Start with Basic , put a bottle of STP fuel system cleaner in atleast 30L of fuel, Buy a new fuel filter it isnt as expensive, check catalytic if choked. Use genuine toyota spark plugs, Do an engine flush before oil change. If the average remains the same there is nothing much that can be done otherwise.
