here's the video:
http://www.youtube.com/watch?v=4UYw4x_VHPI
it's kinda hard to hear with the wind (sorry), but you can hear the engine "normalize" after putting the cap back on the second time.
I honestly don't know if the rpm's were jumping as I didn't look at the gauges when I did it, but it sounded like it was surging..
a failing AOS usually throws smoke at startup, mine doesn't. My cold starts are rock solid and it idles perfectly. Runs fine even on hot starts.
vacuum leak maybe?