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I have a hard start problem. I've replaced basically everything (MAF, sensors, injectors, coils, plugs, etc), yet it persists. WOT also solves start up - get a puff of dark smoke (rich, ya), then I let off and it runs great after that - no other problems. (Before this dumb problem, it ran "ok", now after updating all these parts it runs REALLY well - noticeable improvement in smoothness and power)
When cranking with MAF connected, I get a little signal spike - to around 160 g/sec. So one theory is that the PCM is seeing that, adding way too much fuel and we don't start. If I crack the throttle open, we get enough air to balance with all that extra fuel (just barely bc it's super rich and throwing a code to that effect) and we start.
But what could cause such a weird spike? After startup, the MAF readings are pretty tight at 6.5g/sec. I don't have another car to compare, but seems like the MAF signal should go up mebbe a teeny bit while cranking and stay there. The spike I'm seeing is equivalent to half open throttle...?
You have more than one issue, but the first one you have to correct is your bad IAC. Once you replace that, your other problems may seem more understandable.
IAC seemed to check out in all testing, but I replaced it anyway and did the re-learn procedure. At this point I believe I have tested and replaced every sensor on the motor except for IAT (which is reading correct ambient temp and drops a few degrees after the motor sucks in some air).
I really do wish there was another secret sensor that was causing this start-up problem that I could simply replace. And again, the motor runs really, really well once it is started. If I leave MAF disconnected it has some occasional part-throttle hesitation. Much better with MAF, but then I have to either disconnect it to start-up and reconnect or else start with my foot on the pedal. If I leave MAF connected, it will die after 1-2 seconds - pretty much right when that spike appears.
I've also checked for vacuum leaks and couldn't find any.
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MAF spike at start-up? 
