Nissian infinity 2002 3.0 engine

P0300 Random Misfire code usually indicates a vacuum leak or bad gas. But you can further check below

Misfires can be caused by worn or fouled spark plugs, a weak spark (weak coil, bad spark plug wire), loss of compression, vacuum leaks, anything that causes an unusually lean fuel mixture (lean misfire), an EGR valve that is stuck open, dirty fuel injectors, low fuel pressure, or even bad fuel.