That's right, 5L. If you suspect a misfire in your plugs you should double check your gap and make sure you're absolutely positive that it's gapped at .032" because if you don't, the compression from the turbocharger can extinguish the plasma of the spark at a further gap.
The 7M-GE (non turbo) engines use a much larger gap and can get away with this because of the lack of boost PSI and lack of initial spark advance.
You could also check or replace your spark plug wires (when was the last time you changed them, if at all? How many miles are on those things?). That is a commonly overlooked cause of misfire. Sometimes a spark plug wire conductor core can become brittle over time and crack within the insulation, showing no damage on the outside. Pulling the plug wire from the plug can further destroy a bad spark plug wire. Often times the spark plugs themselves get blamed at the time of change for misfire, when it was actually the brittle wire cores that were further cracked and separated inside the insulation of the wires causing the short and misfire problem.
You could also check your timing on a light (as timing belts do stretch over milage) and check for accordion hose, vacuum and boost leaks and potential leaks coming from cracking or brittle hoses.