I am having a hard time answering you right because you're not articulating your problems correctly. So I can't really say what you're dealing with exactly. A bad IACV can go bad at any time, with or without an FMIC with an open-air or recirculated BOV. I ran my car with an FMIC and open-air BOV with no idle issues. You just have to set the BOV right so that it doesn't cause the car to stall, that's it.
I now run a huge intake manifold with a Q45 TB which has led to idle issues, but I've found out why. It came to a bad IACV and the fact that I might need to run two IACVs in conjunction with each other so that air/vacuum can be properly monitored (this conclusion comes from the experiences of another person using the same intake manifold as myself, but just on a FWD SR20DET).
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