110k miles. Brake booster failed, replaced. Around that time noticed I started plowing through gas. Cleaned k&n and recharged. Changed plugs, carbon build up on plugs and exhaust. Boost is slow/sluggish. Added some chevron techron. MPG is still crap... used to live at around 17-18 around town. I'm driving between 6 to 7k ft above sea level. - Ideas or toughts?...