I have been having this annoying problem for some time now. About 70% of the time, I have to apply the gas while cranking to get it to start. I then let off the gas slowly, and most of the time it stays running, sometimes it doesn't, then I have to retry. If I turn on the AC shortly after, the engine will shut off as soon as I take my foot off the gas. After stopping & starting a few times I can use the AC. I replaced the IAC, this did absolutely nothing. Hasn't gotten better, hasn't gotten worse, its like a gnat that won't leave me alone. Does anyone, oh please, know for the love of good what could be causing this and what do I need to do to make it go away?!

Have you checked fuel pressure at the fuel rail?