Ok well i know there has been a million threads about po171 po174 but I cant seem to find my answer. I drive a 2001 bmw 330ci. Replaced Valve cover Gasket , spark plugs, Both intake tubes, all of my little vaccum hoses, replaced disa gasket, ofhg gasket, air filter. 2 things i havent done are clean the MAF even though I know mines is good and clean the ICV. Other than the car throwing the codes po171 po174 when the engine gets warm whenever i shift from park to reverse or neutral to drive the rpms drop to 500 and rises back up to around 600 and it vibrates the dash. While its in park or neutral it sits silky smooth around 750 rpms. I have gone through a bunch of threads with people with the same issue and no one seems to have a cure or if they did find one didnt post it. Also when im coming to a stoplight the rpms drop and raise like i was explaining. Would a dirty ICV really make it do this? Or am I have other issues I dont know about.