I have a 2004 wrx with 120k on it completely stock. I got a missfire in cylinder 3 a few months ago. I wiped it to see if it would return. It would return in a hundred miles or so. Months went by and I finally purchased my timing kit. On the way home from getting coolant I had to accelerate hard off the ramp on to the highway. Boost seemed fine. I thought I felt a little buck/hesitation previously to that day but I wasn't sure as it was too small to tell. After doing the timing (which was a little off but I got it fixed at the dealer) I took it for a test drive and the car would buck hard when I gave it half throttle or more. Check engine light would come on and off. When it was on it would remain solid for a few days. After a while it just stayed on. Took it to the dealer and they found 6-700 dollars worth of exhaust leaks. Fixed those and the problem persisted. Dealer told me that the car was going into fuel cutout mode because of a bad front 02 sensor. Finally got the front 02 sensor changed yesterday. The dealer said it still had a cylinder 3 misfire. When I got it back the cel stays off but when I give it the throttle cel starts flashing and it still bucks and hesitates. Next step is compression test but I admit I am broke now. Just looking to see if anyone else knows anything of what it could be. I have new iridium plugs that I will install. I just don't think its my plugs that's causing me all this grief. Any help is appreciated.