2003 Toyota Corolla engine has P0302 code

Hi I just had my corrolla ran on a diagnostic machine and it shows a p0302 code which is for a misfire in #2 cylinder from eith spark plug or coil, I replaced all sparkplugs with factory irridium plugs and the#2 coil, and no improvement.
the car idles rough and engine vibrates when running with constant check engine light, when it is driven under load the light flashes when the throttle is engaged, when I let off the trottle after a while it stops flashing and goes to constant lit.
any suggestions, this is starting to annoy me and my pockets thanks.
vehicle is inoperable in its current state.