does it happen when it gets under boost or is it only affected by how much throttle you give it?
if it is when the car builds up boost it probably is spark blow out, this would be cause by bad sparkplugs, bad coil, or the wrong kind of sparkplugs.
for example when i changed the sparkplugs in my GTI i replaced them with cheaper plugs and they caused to much of a voltage drop, i bought some NGK plugs and it worked fine.the reason this happens is because the air is thicker when under boost, so the spark needs more push (voltage) to jump through denser air.
now if it happens in direct connection to the peddle it is probably a bad coil.\
in some cases before they completely die, they will give spark just fine on an idle or on low throttle, however if you open the throttle more it isn't working good enough to send good spark and so the engine misfires.
a good way to tell the difference between plugs and coils is to find out which cylinder is misfiring, (with an obd2 scanner) then swap the coil with one from a different cylinder, if the same cylinder is misfiring it is probably the sparkplug.
good luck and tell us what you find out!