Engine code p1131! Driving me crazy

[sn95bythebay]

I have a 1996 mustang gt with 111k on it. I notice my engine code came on a few weeks ago and it was p1131. I did some research and saw that this check engine light could be a lot of things. The biggest things people told me to check was for vaccum leaks clean your maf and the rear o2. I have no vaccum leak my o2 sensors are turned off with the tune I have and I cleaned my injectors and maf. My car runs the same when the engine light comes on and the same after I clear the code but the light always comes back on after 30 miles or so. What could be causes this light to be coming on? Thank you for your help

 

[Scud2]

I know you said the o2 sensors are turned off in your tune but double check with your tuner. Same thing happened to me. I went to the dyno...got an awesome tune. By the end of the week I was throwing that code. Called my tuner and he told me he turned them off but he would double check. The next day he emailed me with a new tune cuz he forgot. Humans are humans. Just start from there and see what happens. Good luck!

2001 Mustang GT
Vortech V3 Supercharged
402 HP 389 Torque

 

[Nighttrain]

What Scud says, also did you do a smoke test? Not doubting you but a vacuum leak is possible and you dont always hear it