My 2005 WRX has done this since I got it: Every now and then, when I'm accelerating hard, there will be a few (2-5) pops or clicks from the engine and I'll lose a little power. Then it goes away and everything's normal.
The dealer suggested that I wasn't getting 91 octane, but I always have, though I always get the cheap stuff, usually a cheap 76, Valero, or Mobil. I'm in LA, if that matters as far as the gas goes.
Could this really be due to the gas, or does anyone have any other ideas?