engine misses under load
From what I learned, I would troubleshoot the problem by checking the ignition system first, assuming the plugs were good (mine were recently replaced). First I would check that all the plug caps have been snapped on completely, if no joy, then check the cap and rotor for wear or deposits, if they seem OK, then check the plug wires (and the coil wire) for breaks in the insulation and resistance.
If all those things check out, fuel delivery is the next possibility. As there are MANY factors which affect fuel pressure and delivery amounts, it may be logical at that point to have the system and delivery pressures checked by a professional; (I think it is about 1.2 hours of labour by the book). That will permit you to pinpoint what section of your fuel system has the problem.