[1997 legacy bogging down and knock sensor going off]

Thanks guys, glad to hear no one thinks its dying. It is a 97 legacy with about 222,219 miles, driven in AK. Clearly has been beaten up, but has a good heart. Thanks for the inputs!

[1997 legacy bogging down and knock sensor going off]

Hey, just hoping to get a little insight on my new-to-me car. Knock sensor started going off a few tanks ago, so I have added fuel injector cleaner (one btl.) then I've been using octane boosters in succeeding tanks. Now it is bogging down on occasion when at lower speeds and lower rpm. 

I am thinking fuel injector problem, but also, there is loud whistling whine that is noticeable when I accelerate hard (as in passing another car) or accelerate uphill. Also, the knock sensor and the bogging only seem to happen after I have driven the car above 60 mph for a while (longer than 20 min).

I am not much of a mechanic, but my friend is. I'd like some thoughts on where to point him. As of this post, the only code is the knock sensor.