Just going to cut to the chase...first off its a fully built 2005 Mustang GT Stroked & cammed 4.6l 3v with a d1 procharger running around 20psi, also has a full return style fuel system that's rated to 1000horse...I'm at 630rwhp 580rwtq...all the work is done by myself besides the tunning, but the tunning was done at a "world class" proven tuner, but I will leave the name out for now until I figure out whats happening.

Im having a couple issues and I am trying to 1. figure out where to even start looking for an issue, if its tune related or sensor issue and 2. cover all my basis and get as much info as I can together before I contact my tuner or another tuner if I have to.

So my car is running super lean when I come to/am at a stop, so lean my wideband just goes blank, but on the other side of the spectrum there has been days where it is running so dumb rich it mis-fires and carries on. However the lean issue happens pretty much everytime I come to a stop. first start up and idle are fine.

I have a bunch of data logs and videos of this all happening, I will post youtube links to the vids below.

Im new at reading logs and what some of the info means, but I can tell for one my o2's are pegged lean when this happens and my trims seem pegged high, but yet the car never seems to change or "catch itself" until I give it throttle, but even then if I let off It will just go straight back to lean.

I had heard once that it could be a MAF issue, so I went out and bought a VMP maf, but haven't installed it yet since it would have to get another re-tune and to be honest in my logs the MAF doesn't look to horrible if Im looking at it right. my current MAF set up is the stock MAF thru a MAFia which I'm not really fond of anyway.

If anyone could help me out and give me some insight or where to start digging it would greatly be appreciated, I'm a mechanic and built this car and know it like the back of my hand, but when it comes to reading logs, certain sensors, and tuning I'm a complete newb. If anyone wants to see screenshots of the logs, just let me know what to select/highlight and I can post them. but for now here are some videos of when its happening.... If anymore info is needed/wanted let me know

https://youtu.be/5q-cH7v8oFo

 

it does not sound tune related to me, but i could be wrong.

i would probably do a data log with RPMs around 2000, then look at the Short Term Fuel Trims
in the log, to see how that looks.