The P0300 fits right in with the hesitation, and it's no surprise to see that show up. If there was enough oil in the wells, that's a fairly likely candidate for what you're seeing. I think it's definitely worth a shot at installing new plug wires, especially since it sounds like they've never been replaced. But you need to get as much oil as possible out first - a clean rag swabbed around the wells with a screwdriver can get most of it. And just as important is to get the valve cover gasket replaced asap, or else this same thing is likely to happen again within a year or so. If you don't feel comfortable doing a DIY on this, any decent shop can do the job very easily.
Of course, the misfire could be the result of another problem, but the wires are routine maintenance that should be done in any case, so it's best to do that first. Has the plastic thermostat housing been replaced and the timing belt changed? (separate topics having nothing to do with your current problem).