goes into open loop at warm idle?

Hey guys I'm having an issue with my idle when the car is hot. I posted a bit about it in a knock/timing thread but is better suited here. On the logger the o2 graph fluctuates nicely while cruising around 2000 rpm and then when I drop down to an idle when the car isnt fully warmed up it idles around 1100 in closed loops and the o2s fluctuate again nice and smoothly and the idle is smooth. Then all of a sudden after sitting for that extra minute at a red light, the car warms up to full temp and the idle slows to a nice 750. however right when it drops so does the o2s down to about a constant 0.05-0.07. my AF gauge has one red bar and then if I look at the short term o2 fuel trim its reading like 160%! my low fuel trims are maxed at 139.8! then all of a sudden the o2 fuel trim reads 100% and the o2 voltage drops to 0.0-0.01v. Now if I'm not mistaken that means its in open loop mode. it idles like crap like that aswell. my mas had been hacked by the previous owner and my theory is its pulling air the ecu is not accounting for and causing it to run lean. is this possible to cause the computer to flip back to open loop. and yes i have leak tested is and only have some minor leaks in the TB seals. also the coolant temp appears to be reading right on the logger. So what do you guys think. I'm at a loss with this! Thanks for your help guys!