Another turn in the plot.
I took the car to the $tealer$hip for a diagnostic yesterday morning. The emissions still fails but is MUCH MUCH lower. Here's the read-out:
emission reading limit
HC @ idle 336 220
CO @ idle 3.89 1.20
HC @ 2.5K 184 220 <----PASS!!!
CO @ 2.5K 1.94 1.20
All I've changed since the first inspection is the spark plugs, the O2 sensor and the valve cover gasket. After going to the Dealership (the guy was actully pretty helpful in explaining stuff) I now know I have a leak in my vacuum lines. I know that's not an uncommon problem but..as usual, "any advice you might have is appreciated."
this thread continued here: http://www.bimmerwerkz.com/forum/index.php...t=0#entry371354