Like said above, the tuner will only disable the rear o2's. This is the dilemna I was in about 6 months ago, only my Mach never threw a code. I had afew times of my Mach cutting out under hard acceleration, and the SES lighting came blinking on. I took it to a Ford dealership and they could'nt find anything wrong, but the tech did tell me I had a bank 1 passenger side o2 sensor that was somewhat faulty, and eventually would crap out and have to be replaced, but since it never threw a code the dealership would'nt touch it until it did. Well, as luck had it, my bumper to bumper warranty expired last November and my Mach has never had this problem since or threw a code, but when the o2 sensor finally does fail, I'll have to pay out of my own pocket to get it fixed. If you've got any kind of warranty or extended warranty I'd take it to the dealership and they'll fix it for free, otherwise unless you replace it yourself, it'll cost you some cash.
I cant say what the problem is, I havent looked at the car. But if you are pretty confident that the bank 1 upstream O2 isnt functioning right, just get an O2 and put it in. It really shouldnt take that long, and if done yourself its not that expensive either. I got a bosch replacemant over a year ago when my bank 2 upstream O2 went out; it was like $65 and took approx 20 mins to put in.
check for exhaust leak on the passenger side. Also if you have a misfire on bank 1 and the misfire monitor is not ready then you will only have this code. The misfire monitor will be inop if the KAM was recently reset, it takes a little while to reset the misfire monitor.
KAM = keep alive memory
If you have access to a scan tool with live data check the long term fuel trim and short term on both banks if you add the short term to the long term on bank 2 and it's over 15 percent you will soon have a lean code for bank 2.
If it is less than 10 percent and you have no exhaust leaks or misfires then replace the 02 sensor on the passenger side ( bank 1)