I think any OBD11 scanner with data logging capabilities can watch the MAF voltage.

We need AFR's my friend, get me a video of your AFR while the car is doing this.

Make a 10$ smoke tester, smoke test it.

Once you know you have no Vacuum leaks, move onto the next thing.

Next thing is to check and make sure you BOV are working properly,line has come off, fully closing Etc..

Im assuming you've checked for cracked manifolds? (smoke test will show this)

Could be a waste gate problem too. Again smoke test will tell us.

If you build the smoke tester I will come :)

build one, sykpe me or facetime me, Ill run you through it, and try to Diagnosis it for you.

Thanks for offering to help. I got rid of Skype earlier this week. I hardly use it, and somehow my account got hijacked, and some stranger wanted to talk/spam me.

I'm using UpRev Cipher to log the data. I'm sure I can make a smoke testor using a jar, some hoses, and a small pump. Do I pull the intake filters and plug one end as I feed it? I haven't checked the exhaust manifolds since I didn't have the tools or patience to remove the heat shields. The BOV was shipped to TurboSmart for service and cleaning, and it's working just fine. The lines were fully secure as tight as possible with the zip ties. It's difficult to twist the hose. For the wastegate, I'm sure I'd notice some funky spikes under boost. It's pretty steady.

I've been hearing some "hissing" noise from the PCV with one being louder than the other, so I further tightened the hose and the noise diminished. Maybe that might help a bit.

Here's the log of the engine warming up before performing the idle relearn:
https://drive.google.com/open?id=0B1...jdyNTIzdW5IQkE

This is during the relearn, and I revved it a couple of times before shutting down:
https://drive.google.com/open?id=0B1...jdyNTIzdW5IQkE

Engine restart and let it idle for awhile to observe idle RPM:
https://drive.google.com/open?id=0B1...jdyNTIzdW5IQkE

Shut off, restart, and let it idle even longer to further warm things up:
https://drive.google.com/open?id=0B1...jdyNTIzdW5IQkE

Here's a plot of engine RPM, AFR bank 1 and 2, and coolant temp of the last log. I wanted to see how warm it usually gets before it starts acting up again. I didn't have time to drive around or run the engine, so the fans never kicked in. The next plot is just a a composite image.
https://drive.google.com/open?id=0B1...jdyNTIzdW5IQkE
https://drive.google.com/open?id=0B1...Gh2UHVHcUxaM0U

So far it appears AFR hovers around 14.5-14.8 peaking around 15 while idling. I can't tell much of a difference when it is fairly stable as it warms up and when it starts to surge between 750-900 RPM. From the plots, when the coolant temps hit 86F is when idle surge becomes slightly more noticeable. I haven't driven the car to get engine "hot" to see if it acts up again. Also, from the plots, you can see the engine slightly revving up close to 1k RPM then back to idle after starting it up. It happens as it warms up or or after a warm start.

I think I can relate to this thread:
http://www.the370z.com/tuning/93796-...induction.html

See in 1st post with video Cell posted "Bouncing idle," and that's what I'm seeing.

Just got home from driving around, and it wasn't surging as bad until I briefly floored it in 1st and 2nd. I could've sworn the fans weren't running, but I felt a hot breeze on the driver side. No CEL, but ECU logged P0507 again. The video below explains what happened tonight.
https://drive.google.com/open?id=0B1...WhpbWp2cU9pNE0

Log after coming home:
https://drive.google.com/open?id=0B1...kVMX21ETmI3bUU

After shutting it down and restarting, it doesn't hang at 1k RPM anymore:
https://drive.google.com/open?id=0B1...kVMX21ETmI3bUU

I don't know... AFR doesn't look too much different, but it's in the high 14s and peaking around 15.

FF to 40 seconds. It was fixed with a custom tune. No one could ever explain why it happened on the canned GTM tune.

I'll keep digging until I find time to drop the bumper and do some leak tests. So far I can drive around town (including freeways) without it freaking out if I don't drive it hard. I've had the oil temps hit 190F, so that's quite a bit of driving. It's still hunting, but between 750-850. MAP sensor isn't too expensive to replace, but I'm going to do some more reading. The next time the car gets lifted I'll try to check the intake manifolds as well.

The reason why I suspect the MAP sensor is because I soaked it in soapy water. I didn't think it would harm it since it looked sealed.

I'll be taking the car to the shop tomorrow to install new spark plugs, 1000cc injectors, fuel pump and a new custom ECUtek tune. I'll let you know if they fix the problem and what was it exactly. :tiphat:

On a relatively cool (under 50F) drive to work this morning I could not get the engine to freak out after stomping the pedal a few times (peak boost 9 PSI, RPM around 4-5k). It hunted a little around 750-850 RPM as usual, but none of the high idle weirdness after brief hard driving. No codes either.

It'll hit 60F for the high today, and I'll see how it goes from there. I'm getting some logs for a friend, but I don't have the parameters he's looking for (engine load, fuel trim, etc.).

Did you ever find out what was causing your weird idle?

Well this was a nice, informative and highly detailed thread until OP abandoned it…

Did you ever pin this down?

His plastic waffle intake was leaking. Can't remember if he replaced it or new seals. I think he replaced it.

His intake plenum? Interesting! Thanks