This as posted 10-14-2012 lol i got it fixed since then

 

I have exactly the same symptoms with my 2001 Suburban right now. Starts easy, then high revs for a second then rpms are up and down until it is warm. Sometimes it will act like it wants to die at stops but doesn't.

I'm interested in what the whole list of items you went through to fix your issue were. The dealer diagnosed it as a manifold leak but I have trouble buying into this as its too inconsistent. Seems electronic to me.

 

Check my recent post about this, i did replace the intake gaskets myself and it fixed the problem, just get a good set like fel pro like $80 but worth it and it will fix your problem!