Interesting points. Reason I think iac is if it was stuck closed, it wouldn't get the air it needed to idle until I cracked open the throttle.
It might help to have a more complete picture. The IAC is fully opened after engine shutdown then moved in to the park position. After startup the valve is slowly closed so the idle speed will decrease. If the IAC is working when warm but sticking cold then the idle cold should be high. If the IAC is not working warm or cold you'd generally see problems with stalling when warm, especially when shifting to drive or coming to a stop, and you might have no starts or hard starts. I've seen few IAC troubles with TBI but the six liter engines in our vans do have problems. Typically the engine idles slowly warm and won't start or starts and stalls when cold.

It does smell rich, perhaps I need to watch the injectors when it acts up, can they hang open when clogged?
I've never seen that but I can't say they won't do it. What I've seen is a poor pattern. You can watch injector pattern with a timing light. Connect the light as you would to check timing and aim it at the injectors.