Re: P0300 Random misfire - HELP!!
Google that code and you will find the possible causes, P0300 is as you say a random misfire and not caused by any particular cylinder.
Along with the mystery codes you should get a good idea of the cause, continued use when showing this code can cause damage to the engine.
Come back with the mystery codes and you might get better help.
Check the plugs and cables if you want something to do.