pangrastan

Thanks for the clarification; turns out what I suspected to be an O2 sensor was the MAF. I need to get some pictures to clear up locations and descriptions of all of the components. Thanks again.

Thanks for taking the time to respond. As far as I can tell, both online and in the stores, Haynes doesn't have anything for Subaru past '98. Do you know of any others?

From a previous and now somewhat buried post... I have an '02 2.5RS and am trying to find out: What is "IAC?" How can I locate the oxygen/MAF sensor(s)? (links to pictures would be wonderful) Where can I find a good, or at least decent, maintenance manual? Thanks again.

Thanks all for your advice. I changed the air filter two days ago, and this seemed to help a bit. After checking the security of all of the intake ducts to the air filter unit, the noise under the hood is decidedly more of a growl when accelerating. Is that what all of those different ducts do; tune the noise? Anyway, I'm a bit of a neophite when it comes to looking under the hood. What is IAC? How can I locate the front oxygen sensor? Can it be replaced without going to the dealer (one tiny little dealership, one huge conglomerate, neither do I really trust)? Wouldn't the CEL be on if the sensor was bad? Where can I find a good, or at least decent, home maintenance manual? Thanks again.

My '02 Impreza 2.5RS has developed a problem. At highway speed it has a tendency to lose power, then recover. When starting from a stop, it "hiccups" several times before settling into a relatively smooth acceleration. At idle, it slows from 1100rpm to 600, then back to 1100, then to 500, then 1100, then 400, almost dies, back to 1200, and if I let it go long enough will eventually die. The hesitation and stalling during acceleration and at speed are worse if I let it do its idle dance long enough (as after being stopped at a light). I found that the hose connection to the air filter assembly was loose, although I've never touched that, and the air filter had a good amount of "oily" residue (just replaced it) and an unexplained hole, like a rock had gone through the filter. Originally I thought it was water in the fuel filter, as with my first '84 1600 sedan, but that is unverified at this point, as, without a manual, I can't locate the filter. Further, I've read on this site some post re: MAF contamination and the resulting mixture problems. Any thoughts or advice would be appreciated. Stan