Hi, My '82 733i is acting strange. The idle speed is about 1100 when in gear at a stop light, and it rockets up to 2500 when I put it in Park. The crappy Chilton's says to disconnect the air hose from the throttle housing to the charcoal filter and plug it off, then adjust the co2 mixture screw on the side of the throttle housing to proper mixture. Where is this screw? Any help would be appreciated. Thanks!