yes im running same fuel through both engines and its a brand new gallon of fuel i bought 2 days ago i have presure and fuel lines split off the one tank i dont think presure is a problem same with fuel lines and both plugs are new, in my gallery of photos there is this mammoth with 2 silver heads it was set up slightly different but i never had this problem and yeah as far as the left engine getting hotter i to am stumped ive checked lsn and hsn settings and idle screw settings both are the same. ill check for an exhaust leak