I have recently put back together my z and it started up on the first turn. Shortly after, the engine light came on and the car idles rough at times. When left alone, it stays at a constant rpm and does not fluctuate. However, If i do rev it up and allow it to drop from a high RPM, it will get as low as 200rpms and at times even die as the rpm needle drops low enough to kill th engine. I have just replaced both cats with newer ones, (60K oppose to my clogged ones at 127K). I also went around and checked the hoses for leaks and was unable to detect anything. I even tried to spray a little stater fluid in case I was missing something around the hose connections. One thing I did not check was the perimeter of the plenum for any leaks.

What was done to the engine is as follows:
I changed both cylinder heads due to issues with one having bent valves. On the other head, I had a snapped cam shaft ( long story) so I replaced the head since it was cheaper/same price to get a complete used head then used cams. I had done the timing myself and do not think that it is off. Reason being, after assembling the chains, tensions and guides, I had turned by hand the engine over maybe 10-15 revolutions and the teeth markings matched up again with the chain markings. As a last resort, i will take it apart, but I would like to rule everything else out along the way, starting with the sensors. Also, I believe that the car is running rich. I will attach screen shots of the OBDII read outs I had from driving the car around. The LTFT is at 14.8 and 10.9 . I included also the log that was collected during my drive as an excel sheet. If anyone can make sense of it or could tell me what may be causing these issues, it will be greatly appreciated!

I just wanted to know if I did this right and if my readings are what they should be. Using a harbor fright volt meter, I had set it to what you see in the image. by placing the positive and negative leads on the pins, as follows, for each sensor, I got the values you see. The vehicle is a 2004 350z.

pin1 positive lead and pin2 negative lead
pin1 positive lead and pin3 negative lead
pin2 positive lead and pin3 negative lead


Here is a link to my dropbox https://www.dropbox.com/sh/t0x30ot8ktvm ... VLFea?dl=0

Sounds to me like your bank 2 VVT solenoid has crapped out on you.Not an uncommon problem with these engines.I usually replace both of them at the same time.

Welcome to NICO!