Just went thru the same thing. Posted in technical discussions under "OK, Yet another Intermittent Dying-at-the-Light Thread: (sorry, couldn't get safari to copy the link). So far it looks like the big fat hose from the mass airflow was loose. Tightened it up & as of this morning I've put about 75 miles, running smooth & no more off the drop-off in idle like you described. I'll post an update at that post after a few more miles. My driving is city right now, but I am going to Ouray later this month so i wanna make sure it's right for the road.
Anything worth doing is worth getting carried away with(ancient druid saying)