Re: P0300 Random misfire - HELP!!
What are the other codes ? P0300 is a generic code but P030x (x=1:6) tell which cyl is an issue.
Most usual cause is a high voltage (coil, wires, plug) breakdown and they usually start small then get worse.
That last non-zero digit says which cyl it is (and a P030x just means the computer detected a rpm slowdown when that cyl was supposed to fire so could also be mechanical) but need to know what those other codes were.