0300 is the random misfire code.
It means that your engine is misfiring, but that the problem is not isolated to one or two cylinders, it is jumping around in a random way from one cylinder to another.
A random misfire code usually means the air/fuel ratio is running lean but the cause might be anything from a hard to find vacuum leak to weak coil packs.
If you require a set of preowned coil packs then I have loads.
Hope this helps,
Alex.