Clean the throttle body first. (disconnect battery while you have it off.) Pay particular attention to the IAC, and its well.

Test TPS too.... sometimes they can go bad, and cause pretty much the same symptoms.

 

Add mine to the list, does the same blooddy thing. Idles at around 1k when started, when closed loop kicks on it starts to idle like crap, 30 sec later it smooths out and settles at around 600rpm.

Ive replaced both O2's and the IAC, niether helped AT ALL.

Ive just learned to ignore it.

 

What brand O2 sensors?

 

Bosch!!! Because our trucks LOVE Bosch O2 sensors, I also use Bosch Spark plugs and have a "Powered by Bosch" Sticker on my bumper..........

They are NGK Sensors...

 

And it still runs rough, even with the sticker??? That's Unheard of!

Trouble is, there are so many sensors and such with the fingers in the pie for fuel mixture. Any one of which could be the culprit. It sure sounds like the O2 heaters aren't quite doing their job though.....

 

I just try to get the darned thing moving before it has a chance to hit closed loop at idle Problem solved.

 

Mine was doing this or something similar to it, it was doing it whenever i came to a idle, warm or cold, and it got bad enough it would let air in to start it without adding throttle, so i replaced the IAC, that fixed it, sort of. Mine started doing the same thing OP has stated about firing it up, waiting for a little bit and then mine also drops to maybe 200-300rpms and i hear the same air leak/sucking noise.

A week or so ago my truck threw a CEL up for upstream o2 wiring, not the sensor itself (but it may very well be the culprit) but the CEL went away after a couple days

 

Mine did this on a cold start when I got the truck and it had 74000 miles.
I replaced the upstream o2 sensor for the heck of it a couple years after I got it with a Bosch.
It still did it.
Just last year I replaced them both with NTK sensors because of an intermittent (and annoying) CEL for the downstream o2 sensor .
It still does it.

 

I think I'm going to replace the upstream 02 and clean the throttle body. I also just ordered my hughes plate. Unfortunately I live in Texas and it's 100 degrees right now. And I doubt it will get cold enough for me to see if I still have a problem until December. Lol.

 

Cold start means that the engine hasn't ran for a half a day or more. Mine still does it when it's hot outside.