My car is a 2003 Subaru WRX with 98k miles, stock except for the up-pipe(installed when I bought it), I always use good gas in my car and haven't had any major problems like this since I got the car last year. The problem started about two weeks after I changed my spark plugs, which I later found out were gapped wrong and seemed to be the causation of my problem. It first misfired when I was getting on the highway and was at fairly high RPM(5-6k), there was a loss in power and the blinking CEL, which I've read and know is a misfire. Over the last day I've switched to a new set of properly gapped plugs but after the engine runs for a while I get a misfire all over again(haven't left my drive-way). Other than the new plugs and a visual inspection of the coil packs, I haven't done anything else to fix the problem because the alternatives all look expensive and I can't even pinpoint the problem as of now. I've been looking on other posts but I figured I should start my own instead of stealing somebody else's, so if anybody has any input it would be greatly appreciated, Thanks.
And if I'm missing any specifics, just say so