Car randomly dies while coasting

[Tigerinstincts]

So the other night when I shifted into neutral, my car randomly shut off on the freeway. It only happens at higher speeds and never happens in city driving. Basically I was driving at around 80mph and when I threw it into neutral, it idle hunted between 500 and 900 rpm then just died. I turned the ignition on again and it was fine. I have a fidanza flywheel and I believe my wheel speed sensor is going out. Is this most likely my problem or is there something I'm missing?

 

[Koob07]

What modifications other than the flywheel? Mine does this every once in a while but I just need a tune >.>

 

[Tigerinstincts]

Stock turbo, 3 in catback exhaust, hard upper IC piping with Greddy rs BOV. I did a boost leak test and there's minor leaks at higher than 15 psi from my boost controller. But anything lower than that holds. The thing is that Im not boosting at all and just lightly accelerating and when i kick it into neutral, it struggles to idle while coasting coming from 4k rpm. Lower rpms likes 3k hold better but that's because I'm usually not going 70mph or higher.
I thought maybe it was my BOV not opening fully cuz i had that happen before but it did it at all coasting situations and I've since adjusted it and it has never done it since. Also it does not do it all the time. Sometimes it saves itself but sometimes it doesn't.
Is your speed reading correctly on your speedometer? I'm wondering if the ecu uses this to adjust idle and I've noticed mine reads 10mph higher but seems to be accurate at anything over 65 really. Idk I'm just trying to give as much info as possible, this is really strange.

 

[synthetek]

It can be caused by a light flywheel or a bad ISC.

 

[Tigerinstincts]

I'll have to test the ISC then but wouldn't it have other symptoms if it was going out. It has no trouble idling at red lights or shifting into neutral from city driving and doesn't try to catch itself. Just at highway speeds and usually when I'm doing 80mph or faster. It has happened at around 70mph but it can catch itself but not always. It's more likely to happen at higher speeds tho

 

[Koob07]

I had a greddy bov with my stock IC setup, just switched to the punishment racing fmic, s16g and a tial bov. I gotta say my car seems to like it better this way, easy idle and doesn't die as easy like you are describing. I may have had a slight boost leak in the stock setup. But its off to the tuner pretty soon here for me!

 

[Tigerinstincts]

Yeah mine hasn't done it recently at all and I've taken it on the freeway up to 100 and let her coast in neutral and I've been fine. I did fix some minor boost leaks since my last post but idk, it seems to have fixed itself I guess. Quite a strange problem I've ever encountered. I'm wondering if the heat from extended driving and vibration makes the boost leak more apparent at higher speeds and only really causes a problem at these conditions.