cavalier z24(ld9) misfiring?

i have a 2002 cavalier z24 and while driving home the other day, i tried giving it some gas to get up to normal speed, and it started sputtering. the CEL started flashing, so i pulled over. At idle, it does not misfire as bad, its when the engine is loaded. i replaced the spark plugs and connectors and cleaned the map sensor ( or maf whatever it is). i took it to my mechanic and he didn't find anything. the car now does not misfire at idle or when the engine is slightly loaded, but it does when i try giving it more than 1/2 throttle in a lower gear.

P.S. i had the icm checked a couple months ago and it was fine. i also inspected the coil housing, seeing how this gives people alot of trouble, and it looks fine. no cracks, just a bit dirty. also the connecting points look good. i had a scanner plugged in and it showed a p0300 code- random misfire.

my question is, could it be the coil housing that's causing a misfire, despite it being in good visual condition? or could it be the ICM? I should also add that i don't think its a coil because it would be misfiring in two cylinders, and it suredoesn'tt feel or sound like two cylinders are missing. thanks in advanced for your responses.