So I bought my 08 WRX about 6 weeks ago. It had 46k miles and has 47.8k now. I have done an oil change and coolant flush. A couple weeks later a P1071 code came up (system running too lean) popped the hood and my COBB intake (on the car when I got it) seemed loose so I tightened it and it went away. But now my car seems to have lost a slightly noticeable amount of power and my turbo flutters. By that I mean when I coast at 3.5k rpm and punch it my rpms will flutter all the way up until I change gears. Also the car has always seemed to idle a little rough. I've been told turbo leak, inlet leak, and spark plugs. Haven't been able to find much relevant info online. TODAY I got in my car and the MPG gauge on my dash read 15.3mpg when it has always been 19.2. Anyone had this same issue before?