If a replacement Knock sensor is a genuine Subaru part?

 

My Legacy has developed a small loss of power over the past few days. It's mostly between 1500 and 3500 rpm, and its not a large loss, but its evident enough that passengers in the car can feel it. Above 3500 it seems to be back to full power. I thought it was just in my head until a friend of mine pointed it out today. Best way I can figure to explain it is, it feels like I backed off the throttle about 5-10%. It's there in all gears, more noticeably in lower gears, (as is generally the case with any sort of power loss) This can be felt with the cruise control on as well, especially if climbing a hill.

 

I can see that the knock sensor is practically brand new on this thing, the fuel filter also looks to be fairly new, but I'm thinking a replacement is in order anyway. It kinda seems to have a bit to do with throttle input, so I'm going to swap in a TPS I got on my last JY run and see what happens. Might even make a trip back to the JY and grab another MAF and an O2 sensor or two.

 

Ideas?

What markings can I look for on the Knock sensor to determine if its a Subaru part?

Knock sensor would cause probs at high RPMs and load. Not so much at lower RPMS, adn if it were bad enough to affect driveability it would be setting a code.

 

I am thinking MAF

Well, tossed another MAF in it, and it doesn't seem to have fixed it. It isn't doing it quite as often, BUT, its also about 15 degrees cooler today than it was friday and saturday when it was really bad.

 

I guess the front pipes of the exhaust system on these cars rust out really often, not a single legacy in the JY had the front pipes. So no O2 sensor to try on this trip. I did get a knock sensor that looked relatively new, and an ignition module just for kicks. I'll give those a shot since neither is difficult to swap.

 

I'm kinda starting to wonder if it's a fuel issue. The past week or so it seems to take longer and longer to start when cold. When the engine is warm it will fire up in about a second. But on cold starts it's taking up to 5 seconds of cranking now before it will fire.

I have a new lead. CEL popped on last night after driving down some gravel roads on the way home. Scanner pulled a P0106 Map/Baro sensor circuit/range/performance.