Need mechanical advise. Low power.

I have a 2009 Subaru Impreza 2.5i. 5speed manual. Current issue is low power and/or hesitation on the upper rev range. Sometimes starts as low as 3500 rpm. This causes issues getting onto freeways and makes passing near impossible. Car also makes a strange crackling noise like a handful of small rocks jiggling in a tin can only when above 3500or4000rpm.

Had a DIY hybrid intake on the car, just replaced the pipe from airbox to TB. Took it to subaru thinking it was an exhaust issue. They found no problems with the exhaust but blamed the hybrid intake. I took it off this past weekend and replaced it with the stock intake. Even after following the ecu reset trick it ran better but still low on power. Today I replaced the spark plug wires, which gave me back some low end torque but the high end is still really struggling. I'm talking the car wont go to the top 2 grand of the rev range. Hesitates on its way there with that noise.

Its drivable now, I can get to 55 and 65 easily but 70 is a struggle. Even cruise control struggles. Gas mileage is down too.

Car runs fine no drama driving like a granny, but not much more than that. Oil was changed last month 5w30 rotella. No check engine lights.

Any idea?