So I was messing around with the interior of my car this passed weekend so I removed the (-) battery. I merely took my door panel off and replaced the small vent/fan inside. so, the (-) was removed for maybe 3 hours at most. (im slow)
The point is, today I started my car and the idle sunk way down and the engine shut off. I had already drove the car in the morning and it had no problem so the engine was warm. But it kept up the same problem a couple more times later in the day. So, I did some research and reset my ECU using the pedals. the idle still sinks way down but doesn't shut off anymore. I'll be trying it again tomorrow morning when it's cold.
I also noticed that my oil pressure was a bit low. around 25 idle and about 60 at 3k rpm. now all engines are different so that might be normal for some but it seems a bit low for mine. Like i said, I'm going to start her up tomorrow to see how it is cold but i still feel like there's something wrong. If the problem persists even with a cold engine, what should I do?

 

25psi isn't bad for idle since the minimum is 14. 60psi at 3K seems low to me, but not to the point of worrying about it. The SM calls for at least 43 at 2K and 57 at 6K, so you're well within specs..

Mine runs 60 at 2K and idles at 30 warmed up, but it's got very low miles.

 

So this is an update. It's the next day now and the problem "persists" i guess you could say. My oil pressure doesn't seem low now that I actually pay much more attention to it. Maybe a little but within normal range. HOWEVER i did notice something important. If it's a cold start, as in I haven't started it for at least a couple hours, it starts fine completely normal. It is when the car is at a warm start, as in I just drove it about a half hour ago, that it does the issue. I am going to get it serviced very soon. Change the oil, what not. Have them look the car over. But for now I believe it has to do with the oil because it is only on warm starts. Anyone have an opinion?

 

Search "idle relearn" or something like that. Seems like there's a procedure for getting the ECU to correct your problem.

 

Here:
https://my350z.com/forum/6008226-post2.html