As I was futzing around with my van today (doing an oil change -- a
friend suggested using a heavier oil with my power-loss problem, and I
put 20W50 in, which is perfect for my move to Arizona), I realized
that one of the things that my friend and I had done was to open the
AFM and change the rotation on the spring-carrier.  Since we did that,
the thing was slightly stuttering and hesitating.

I decided to crack it back open and reset it to what it was -- and it
started running better, but the exhaust scent was off (it smelled like
it wasn't burning all the fuel properly).  On a hunch, I cracked it
back open, and moved it another prong toward loosening it up.

Now, the exhaust smells a bit more 'normal' (less rich, more carbony).

I know that "the designers seal the AFM for a reason", and that you
really shouldn't mess with it without knowing what you're doing... but
this trial seems to suggest that the spring on the AFM was preventing
my engine from getting as much air as it needed to combust the fuel?

Is there anything wrong with this line of reasoning?

I'm driving from Chicago to Madison tonight, going to see if the
throttle cleaning and AFM spring resets help at all with the "loses
power after 30 minutes on open highway" problem I've been having.
Wish me luck. :)

Thanks again for all your help!

-Kyle