Long story short: My lexus came with a uninstalled JDM CAI that I had to modify such that I could install the MAF sensor (JDM 2jz's come with a MAP, not a MAF). Well that didn't go over too well and the MAF wouldn't seat right. As a result the car would start and often idle fine, but once put in reverse it would immediately stall. After minutely adjusting the position of the sensor I could often get her out on the road, although she would still routinely stall/randomly bog down depending on how it (MAF sensor) was "seated". On one occasion I got the MAF seated just right and my lord, did that car take off like a bat out of hell. :bangbang:
Eventually I got sick of fucking with it and put the MAF back in it's original housing, and "jury-rigged" the rest of the CAI. Haven't had a problem since.
Not sure how much that helps but yea, i'd definitely take a close look at the MAF sensor. Perhaps the CAI (and/or lack of AITS input) is causing the MAF to malfunction?
If you want to try and throw parts at it I would think a used MAF for that vehicle could be found at u-wrench-it for under $20, especially this time of year.
And mensan I can't help but laugh everytime I see your avatar...Poor noobs lulz.