Hi, when you have the option of live data it should be possible,if not you need a more 
extensive scanner,but po300 code means multiple misfires detected ,this means the 
misfire is not on a specific cylinder, but randomly, this could be caused by  a too lean 
fuel mixture due to fals air coming into the engine due to a bad pcv  valve or crater 
hose or a bad maf sensor connection,check clamps.