Hi Everyone, Problem with my 2001 E53 4.4. On a Cold start, engine Idle rpm will hover around 800, at warm to full running temperature, engine rpm stays at a consistent 1100-1200. (Transmission in park or neutral, of course when in gear it'll drop to 700-800 rpm). Yes, there are two codes: P0174 and P0171. Indications of Banks 1 and 2 running too lean. Perhaps a vacuum leak? If it was a vacuum leak, wouldn't it have a high engine rpm no matter the engine temperature? What common denominator would give a lean condition to both banks? My thoughts have "leaned" towards the throttle body. Took a peak at the throttle body, found that the throttle plate is not completely closed (key off/eng off). Shouldn't the plate be closed completely? Hoping someone can enlighten me on this plate. P.S. The engine runs great, very strong running, even with the lean condition. Thanks to todays engine mgmt. No doubt, Stoich